Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. 문제 설명

10 5
1 2 3 4 2 5 3 1 1 2

2. 투 포인터 기법 적용

• end 포인터가 계속 늘려가면서 합의 값이 M이거나 보다 크게 되는 구간까지 늘립니다.
• 구간합이 M보다 작아지는 지점까지 start 포인터를 늘려 갑니다.
• 합의 구간이 M이 되는 경우 result값을 한개씩 증가합니다.

3. 투 포인터 그림 설명

4. 소스 코드

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
    static int N,K;
    static int[] Arr;
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine().trim());
        N = Integer.parseInt(st.nextToken());
        K = Integer.parseInt(st.nextToken());
        Arr = new int[N + 1];
        st = new StringTokenizer(br.readLine().trim());
        for (int i = 0; i < N; i++) {
            Arr[i] = Integer.parseInt(st.nextToken());
        }

        int i,j;
        i = 0 ; j = 0;
        int sum = 0;
        int count = 0;
        while(true){
            if(sum >= K) sum -= Arr[i++];
            else if(j == N) break;
            else sum += Arr[j++];
            if(sum == K) count++;
        }
        System.out.println(count);
    }
}

while(true){
    if(sum >= K) sum -= Arr[i++];
    else if(j == N) break;
    else sum += Arr[j++];
    if(sum == K) count++;
}

5. 마치며…

함께 보면 좋은 글

• [Algorithms] 위상 정렬 알고리즘
• [Algorithms] BFS, DFS 알고리즘
• [Algorithms] LCA 알고리즘
• [Algorithms] 벨만-포드 알고리즘

The post [Algorithms] 투 포인터 알고리즘 appeared first on WONIZZ.LOG.

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. 위상 정렬 알고리즘 동작 방식

• linecount : 1차원 배열로 해당 정점을 target으로 하는 간선이 몇개인지를 표기하는 변수입니다.
• result : 1차원 배열로 linecount를 하나씩 지워주면서 0이 되는 시점에 해당 변수에 담아 줍니다. 즉, 위상의 순서에 대한 결과입니다.

2. 위상 정렬 알고리즘 소스코드

3. 관련 알고리즘 문제

4. 마치며…

5. 참고

함께 보면 좋은 글

• [Algorithms] 투 포인터 알고리즘
• [Algorithms] BFS, DFS 알고리즘
• [Algorithms] LCA 알고리즘
• [Algorithms] 벨만-포드 알고리즘

The post [Algorithms] 위상 정렬 알고리즘 appeared first on WONIZZ.LOG.

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. 설명

문제

입력

출력

입력예제

6
2 1 2
2 3 3
1 2
1 2
2 1 -1
1 2

출력예제

1
3
3

2. 문제풀이

public static long query(int node, int start, int end, int k){
        if(start == end){
            System.out.println(start + " ");
            return start;
        }
        if(node *2 <= tree_size && tree[node * 2] >= k){
            return ret = query(node *2, start, (start + end) / 2, k);
        }
        k -= tree[node * 2];
        if(node * 2 + 1 <= tree_size && tree[node * 2 + 1] >= k){
            return ret = query(node * 2 + 1, (start + end) / 2 + 1, end, k);
        }
        return 0;
    }

k -= tree[node * 2];

if(node * 2 + 1 <= tree_size && tree[node * 2 + 1] >= k){
    return ret = query(node * 2 + 1, (start + end) / 2 + 1, end, k);
}

if(start == end){
    System.out.println(start + " ");
    return start;
}

풀이

import java.io.*;
import java.util.StringTokenizer;

public class segment_2243 {
    static long[] tree;
    static long[] arr;
    static int N,tree_size;
    static StringTokenizer st;
    static long ret;
    public static void update(int node, int start, int end, int index, long diff){
        if(!(start <= index && index <= end)) return;
        tree[node] += diff;
        if(start != end){
            int mid = (start + end ) >> 1;
            update(node * 2, start, mid, index, diff);
            update(node * 2 + 1, mid + 1, end, index, diff);
        }
    }
    public static long query(int node, int start, int end, int k){
        if(start == end){
            System.out.println(start + " ");
            return start;
        }
        if(node *2 <= tree_size && tree[node * 2] >= k){
            return ret = query(node *2, start, (start + end) / 2, k);
        }
        k -= tree[node * 2];
        if(node * 2 + 1 <= tree_size && tree[node * 2 + 1] >= k){
            return ret = query(node * 2 + 1, (start + end) / 2 + 1, end, k);
        }
        return 0;
    }
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        st = new StringTokenizer(br.readLine());
        N = Integer.parseInt(st.nextToken());
        int h = (int)Math.ceil(Math.log(1000000) / Math.log(2));
        tree_size = 1 << h + 1;
        tree = new long[tree_size];
        arr = new long[N + 1];
        for (int i = 0; i < N ; i++) {
            int A,B,C;
            st = new StringTokenizer(br.readLine());
            A =  Integer.parseInt(st.nextToken());
            if(A == 1){
                B = Integer.parseInt(st.nextToken());
                int getIndex = (int) query(1, 0,  1000000, B);
                update(1, 0, 1000000, getIndex, -1);
            }
            else if(A == 2){
                B = Integer.parseInt(st.nextToken());
                C = Integer.parseInt(st.nextToken());
                update(1, 0, 1000000, B, C);
            }
        }
    }
}

함께 보면 좋은 글

• [문제풀이] 군사도로망
• [Algorithms] 투 포인터 알고리즘
• [Algorithms] 위상 정렬 알고리즘
• [Algorithms] BFS, DFS 알고리즘

The post [문제풀이] 사탕 상자 appeared first on WONIZZ.LOG.

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. DFS 알고리즘

• map : 2차원 배열로 인접 행렬 방식으로 두 노드간의 연결 정보를 나타냅니다.
• visit : 1차원 배열로 노드의 방문을 표기하게 됩니다.

for (int i = 0; i < E; i++) {
    st = new StringTokenizer(br.readLine());
    from = Integer.parseInt(st.nextToken());
    to = Integer.parseInt(st.nextToken());
    map[from][to] = 1;
    map[to][from] = 1;
}

 public static void dfs(int src) {
        visit[src] = 1;
        System.out.printf(src + " ");
        for (int i = 1; i <= V; i++) {
            if (visit[i] == 0 && map[src][i] == 1) {
                dfs(i);
            }
        }
    }

2. BFS 알고리즘

• map : 2차원 배열로 인접 행렬 방식으로 두 노드간의 연결 정보를 나타냅니다.
• visit : 1차원 배열로 노드의 방문을 표기하게 됩니다.

public static void bfs(int src) {
        q.offer(src);
        visit[src] = 1;
        while (!q.isEmpty()) {
            int x = (int) q.poll();
            visit[x] = 1;
            System.out.printf(x + " ");
            for (int i = 1; i <= V; i++) {
                if (visit[i] == 0 && map[x][i] == 1) {
                    q.offer(i);
                    visit[i] = 1;
                }
            }
        }
    }

3. DFS 와 BFS 차이점

• 인접 리스트로 표현된 그래프 : O(V+E)

• 인접 행렬로 표현된 그래프 : O(V^2)

4. 관련 알고리즘 문제

5. 마치며...

6. 출처

함께 보면 좋은 글

• [Algorithms] 투 포인터 알고리즘
• [Algorithms] 위상 정렬 알고리즘
• [Algorithms] LCA 알고리즘
• [Algorithms] 벨만-포드 알고리즘

The post [Algorithms] BFS, DFS 알고리즘 appeared first on WONIZZ.LOG.

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. 설명

문제

입력

출력

입력예제

1
5 3 3
1 2 1
1 3 4
2 3 2
3 5 2
3 4 7
4 5 4

출력예제

7

2. 문제풀이

풀이

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Collections;
import java.util.Comparator;
import java.util.StringTokenizer;
import java.util.Vector;

public class MST_군사도로망 {
    static Vector edge1, edge2;
    static int T, n,m,k; // 3, 3
    static long res;     //long 주의
    static boolean chk;
    static int[] parent;

    //크루스칼 객체 (정점에 정보를 저장하는 객체)
    static class kruscal{
        int from, to, val;
        public kruscal(int from, int to, int val) {
            this.from = from;
            this.to = to;
            this.val = val;
        }
    }
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st;
        st = new StringTokenizer(br.readLine());
        T =  Integer.parseInt(st.nextToken());

        //1. 테스트 케이스
        for (int i = 1; i <= T; i++) {
            res = 0;
            st = new StringTokenizer(br.readLine());
            n = Integer.parseInt(st.nextToken()); //정점의 갯수

            m = Integer.parseInt(st.nextToken()); //연결된 갯수
            k = Integer.parseInt(st.nextToken()); //미연결된 갯수

            parent = new int[n+1];
            for (int j = 1; j <= n; j++)
                parent[j] = j;

            //1. 그래프 형성
            edge1 = new Vector();
            for (int q = 0; q < m; q++) {
                st = new StringTokenizer(br.readLine());
                kruscal ks = new kruscal(Integer.parseInt(st.nextToken()), Integer.parseInt(st.nextToken()), Integer.parseInt(st.nextToken()));
                edge1.add(ks);
            }

            edge2 = new Vector();
            for (int w = 0; w < k; w++) {
                st = new StringTokenizer(br.readLine());
                kruscal ks = new kruscal(Integer.parseInt(st.nextToken()), Integer.parseInt(st.nextToken()), Integer.parseInt(st.nextToken()));
                edge2.add(ks);
            }
            //2. 정렬
            Collections.sort(edge1, new Comparator() {
                @Override
                public int compare(kruscal o1, kruscal o2) {
                        if(o1.val < o2.val) return 1;
                        else if(o1.val == o2.val) return 0;
                        else return -1;
                    }
            });
            Collections.sort(edge2, new Comparator() {
                @Override
                public int compare(kruscal o1, kruscal o2) {
                    if(o1.val < o2.val) return -1;
                    else if(o1.val == o2.val) return 0;
                    else return 1;
                }
            });

            ///////////////////////////////////////////////////////////////////////

            //3. 실제 작업.
            for (int a = 0; a < m; a++) {
                merge(edge1.get(a).from, edge1.get(a).to);
                if(!chk)
                    res += edge1.get(a).val;
            }

            for (int b = 0; b < k; b++) {
                merge(edge2.get(b).from, edge2.get(b).to);
                if(chk)
                    res += edge2.get(b).val;
            }
            System.out.println("#" + i + " " + res);

        }
    }
    public static int find(int u){
        if(u == parent[u])
            return u;
        return parent[u] = find(parent[u]);
    }
    public static void merge(int u, int v){
        chk = false;
        u = find(u);
        v = find(v);
        if(u==v) return;
        parent[u] = v;
        chk = true;
    }
}

함께 보면 좋은 글

• [문제풀이] 사탕 상자
• [Algorithms] 투 포인터 알고리즘
• [Algorithms] 위상 정렬 알고리즘
• [Algorithms] BFS, DFS 알고리즘

The post [문제풀이] 군사도로망 appeared first on WONIZZ.LOG.

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. LCA 알고리즘 원리

• 두 노드간의 depth가 더 깊은 것을 동일 선상으로 맞추는 작업
• 조상배열을 통해서 공통의 조상 바로 밑까지 올리는 작업

2. 초기화 과정

• parent : 2차원 배열로 선언하여, i의 2^K번째 노드를 찾아나갈 때 사용하는 변수 입니다.
• ad : 필자 같은 경우 인접리스트를 ArryList안에 ArrayList로 구현을 했습니다.
• depth : 1차원 배열로 현재 노드의 depth를 타나내는 변수입니다.

2-1. BFS를 활용한 초기 parent 구성

c[1] = 1;
q.add(1);
    while(!q.isEmpty()){
        int x = q.poll();
        for (int i = 0; i < ad.get(x).size(); i++) {
            int to = ad.get(x).get(i);
            int y = to;
            if(c[y] == 0){
            depth[y] = depth[x] + 1;
            parent[y][0] = x;
            c[y] = 1;
            q.add(y);
        }
    }
}

2-2. DP를 활용한 parent 구성

for (int k = 1; k < 17; k++)for (int i = 1; i <= n; i++) {
    parent[i][k] = parent[parent[i][k-1]][k-1];
}

3. 공통 조상 쿼리 과정

//depth를 항상 u가 더 깊게 하기 위해서 swap
if(depth[u] < depth[v]){
    int temp;
    temp = u;
    u = v;
    v = temp;
}
int diff = depth[u] - depth[v];

//두 노드간의 depth차이 만큼 u를 맞춰주는 작업을 수행합니다.
for (int k = 0; diff != 0; k++) {
    if((diff & 1 )== 1) u = parent[u][k];
    diff >>= 1;
}

//두개가 동일하다면 u를 반환합니다.
if(u == v) return u;

for (int k = 17; k >= 0; k--) {
if(parent[u][k]!= parent[v][k]){
        u = parent[u][k];
        v = parent[v][k];
    }
}

return parent[u][0];

4. 관련 알고리즘 문제

5. 마치며...

함께 보면 좋은 글

• [Algorithms] 투 포인터 알고리즘
• [Algorithms] 위상 정렬 알고리즘
• [Algorithms] BFS, DFS 알고리즘
• [Algorithms] 벨만-포드 알고리즘

The post [Algorithms] LCA 알고리즘 appeared first on WONIZZ.LOG.

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. 세그먼트 트리란?

• 수를 바꾸는 과정 (O(logN))
• 수를 더하는 과정(O(logN))
• M번 수행한다고 가정하면, O(MlogN + MlogN) -> O(MlogN)이 걸리게 됩니다.

2. 초기화 과정(Init)

 public static long init(int node, int start, int end){
        if(start == end) return tree[node] = arr[start];
        int mid = (start + end) >> 1;
        return tree[node] = init(node * 2, start, mid) + init(node * 2 + 1, mid + 1, end);
    }

init(1, 0, 12);
1번의 tree Node
0 ~ N(12) 까지의 arr 배열 정보

if(start == end) return tree[node] = arr[start];

3. 갱신 과정(Update)

public static void update(int node, int start, int end, int index, long diff){
        if(!(start <= index && index <= end)) return;
        tree[node] += diff;
        if(start != end){
            int mid = (start + end) >> 1;
            update(node * 2, start, mid, index, diff);
            update(node * 2 + 1, mid + 1, end, index, diff);
        }
    }

if(!(start <= index && index <= end)) return;

tree[node] += diff;
if(start != end){
    int mid = (start + end) >> 1;
    update(node * 2, start, mid, index, diff);
    update(node * 2 + 1, mid + 1, end, index, diff);
}

4. 구간합 과정(sum)

1. left, right와 start, end가 겹치지 않는 경우
2. left, right가 start, end를 완전히 포함하는 경우
3. start, end가 left, right를 완전히 포함하는 경우
4. left, right와 start, end가 겹치는 경우

public static long sum(int node, int start, int end, int left, int right){
        if(left > end || right < start) return 0; // 범위에 속하지 않으면, return 
        if(left <= start && end <= right) return tree[node]; // left,right가 완전히 포함하면, tree정보 리턴
        //그외의 경우는 범위를 쪼갠다.
        int mid = (start + end) >> 1;
        return sum(node * 2, start, mid, left, right) + sum(node * 2 + 1, mid +1 , end, left, right);
    }

5. 관련 알고리즘 문제

6. 마치며...

함께 보면 좋은 글

• [Algorithms] 최소 스패닝 트리(Minimum Spanning Tree)
• [Algorithms] 투 포인터 알고리즘
• [Algorithms] 위상 정렬 알고리즘
• [Algorithms] BFS, DFS 알고리즘

The post [Algorithms] 세그먼트 트리 appeared first on WONIZZ.LOG.

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. 벨만포드 기본 개념

D(s, v) = D(s, u) + w(u, v)

2. 벨만-포드 예외사항

3. 벨만-포드 코드

static class Point{
    // 시작점, 도착점, 걸리는 시간
    int here, there, dist;
    public Point(int here, int there, int dist){
        this.here = here;
        this.there = there;
        this.dist = dist;
    }
}

// 2. 입력값 초기화
for(int i = 0; i < m; i++){
    st = new StringTokenizer(br.readLine());
    int here = Integer.parseInt(st.nextToken());
    int there = Integer.parseInt(st.nextToken());
    int dist = Integer.parseInt(st.nextToken());
    point[i] = new Point(here, there, dist);
}

private static boolean bellmanFord() {
    dist[1] = 0;
    // v - 1번 수행
    for(int i = 1; i < n; i++){
        // edge relaxtaion
        for(int j = 0; j < m; j++){
            Point p = point[j];
            // dist[there] > 현재 정점 + 거리 이면, 최단으로 업데이트 수행
            if(dist[p.here] != INF && dist[p.there] > dist[p.here] + p.dist){
                dist[p.there] = dist[p.here] + p.dist;
            }
        }
    }
}

4. 관련 알고리즘 문제

5. 마치며..

함께 보면 좋은 글

• [Algorithms] 투 포인터 알고리즘
• [Algorithms] 위상 정렬 알고리즘
• [Algorithms] BFS, DFS 알고리즘
• [Algorithms] LCA 알고리즘

The post [Algorithms] 벨만-포드 알고리즘 appeared first on WONIZZ.LOG.

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. 다익스트라 기본 개념

2. 다익스트라의 단점

3. 우선순위 큐

pq = new PriorityQueue();
ad = new ArrayList>();

for (int i = 0; i < E; i++) {
    st = new StringTokenizer(br.readLine().trim());
    int from, to, value;
    from = Integer.parseInt(st.nextToken());
    to = Integer.parseInt(st.nextToken());
    value = Integer.parseInt(st.nextToken());
    ad.get(from).add(new Point(to, value));
}

public static void dijkstra(int src){
    pq.add(new pqPoint(src, 0));
    dist[src] = 0;
    while(!pq.isEmpty()){
        pqPoint p= pq.poll();
        int cost = p.cost;
        int here = p.here;
        if(dist[here] < cost) continue;
        for (int i = 0; i < ad.get(here).size(); i++) {
            int there = ad.get(here).get(i).there;
            int nextDist = cost + ad.get(here).get(i).nextDist;
            if(dist[there] > nextDist){
                dist[there] = nextDist;
                pq.add(new pqPoint(there, nextDist));
            }
        }
    }
}

for (int i = 0; i < ad.get(here).size(); i++) {
    int there = ad.get(here).get(i).there;
    int nextDist = cost + ad.get(here).get(i).nextDist;
    if(dist[there] > nextDist){
        dist[there] = nextDist;
        pq.add(new pqPoint(there, nextDist));
    }
}

4. 관련 알고리즘 문제

5. 마치며...

함께 보면 좋은 글

• [Algorithms] 투 포인터 알고리즘
• [Algorithms] 위상 정렬 알고리즘
• [Algorithms] BFS, DFS 알고리즘
• [Algorithms] LCA 알고리즘

The post [Algorithms] 우선순위 큐 다익스트라 appeared first on WONIZZ.LOG.

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?"

1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?"

Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

1. Heap이란?

• 완전 이진 트리의 일종으로 우선순위 큐를 위하여 만들어진 자료구조 입니다.
• 여러개의 값들 중에서 최댓값이나 최솟값을 빠르게 찾아내도록 만들어진 자료구조 입니다.

1-1. Heap의 구현

• 힙을 저장하는 표준적인 자료구조는 배열입니다.
• 구현을 쉽게 하기 위해서는 첫번째 인덱스인 0은 사용하지 않습니다.
• 힙에서의 부모 노드와 자식 노드와의 관계
  • 왼쪽 자식의 인덱스 = (부모의 인덱스) * 2
  • 오른쪽 자식의 인덱스 = (부모의 인덱스) * 2 + 1
  • 부모의 인덱스 = (자식의 인덱스) / 2

1-2. heap 의 삽입

1-3. heap의 삭제

2. Priority Queue란?

2-1. Priority Queue의 구현

 public class Sample {
    public static void main(String[] args) {
        PriorityQueue pq = new PriorityQueue<>();
        pq.add(4);
        pq.add(19);
        pq.add(2);
        pq.add(1);
        System.out.println(pq.poll()); // 1이 출력된다.
    }
}

public class Sample {
    public static void main(String[] args) {
        PriorityQueue pq = new PriorityQueue<>(Collections.reverseOrder());
        pq.add(4);
        pq.add(19);
        pq.add(2);
        pq.add(1);

        System.out.println(pq.poll()); // 19가 출력된다.
    }
}

2-2. Custom 객체에 대한 우선순위 큐 적용

class Prisoner {
    String name;
    int weight; // 형량

    public Prisoner(String name, int weight) {
        super();
        this.name = name;
        this.weight = weight;
    }
}

class Prisoner implements Comparable {

    String name;
    int weight; // 형량

    public Prisoner(String name, int weight) {
        super();
        this.name = name;
        this.weight = weight;
    }

    @Override
    public int compareTo(Prisoner target) {
        if (this.weight > target.weight) {
            return 1;
        } else if (this.weight < target.weight) {
            return -1;
        }
        return 0;
    }

private static PriorityQueue getPriorityQueue() {

    Prisoner prisoner1 = new Prisoner("james", 5);
    Prisoner prisoner2 = new Prisoner("schofield", 99);
    Prisoner prisoner3 = new Prisoner("alex", 14);
    Prisoner prisoner4 = new Prisoner("silvia", 10);
    Prisoner prisoner5 = new Prisoner("thomson", 1);

    PriorityQueue priorityQueue = new PriorityQueue();

    priorityQueue.offer(prisoner1);
    priorityQueue.offer(prisoner2);
    priorityQueue.offer(prisoner3);
    priorityQueue.offer(prisoner4);
    priorityQueue.offer(prisoner5);

    return priorityQueue;
}

public static void main(String[] args) {

        PriorityQueue priorityQueue = getPriorityQueue();
        System.out.println("=============== Normal Order");
        while (!priorityQueue.isEmpty()) {
            Prisoner prisoner = priorityQueue.poll();
            System.out.println(prisoner.name);
        }
}

=============== Normal Order
thomson
james
silvia
alex
schofield

3. 관련 알고리즘 문제

• 자료구조 기본 문제

4. 마치며..

5. 참조

함께 보면 좋은 글

• [Algorithms] 투 포인터 알고리즘
• [Algorithms] 위상 정렬 알고리즘
• [Algorithms] BFS, DFS 알고리즘
• [Algorithms] LCA 알고리즘

The post [Algorithms] Heap, Priority Queue appeared first on WONIZZ.LOG.