[백준/JAVA] 1260 DFS와 BFS

DFS와 BFS

백준 1260번 DFS와 BFS 문제 링크

풀이

• 인접 행렬 arr
• 들렸던 노드 체크 check
• DFS는 재귀로 구현
• BFS에 사용할 큐 q로 구현

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제출 코드

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

class Main {
    public static boolean[] check;
    public static int[][] arr;
    public static Queue<Integer> q = new LinkedList<>();
    public static int N, M, V;
    public static StringBuilder sb = new StringBuilder();

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        StringTokenizer st = new StringTokenizer(br.readLine(), " ");
        N = Integer.parseInt(st.nextToken());
        M = Integer.parseInt(st.nextToken());
        V = Integer.parseInt(st.nextToken());

        arr = new int[N+1][N+1];

        for (int i = 0; i < M; i++) {
            st = new StringTokenizer(br.readLine(), " ");
            int a = Integer.parseInt(st.nextToken());
            int b = Integer.parseInt(st.nextToken());
            arr[a][b] = 1;
            arr[b][a] = 1;
        }
        check = new boolean[N+1];
        dfs(V);
        sb.append("\n");

        check = new boolean[N+1];
        bfs(V);
        bw.write(sb.toString());
        bw.flush();
    }

    public static void dfs(int start) {
        check[start] = true;
        sb.append(start).append(" ");

        for (int i = 0; i < N+1; i++) {
            if (arr[start][i] == 1 && !check[i]) {
                dfs(i);
            }
        }
    }

    public static void bfs(int start){
        q.add(start);
        check[start] = true;

        while (!q.isEmpty()) {
            start = q.poll();
            sb.append(start).append(" ");

            for (int i = 0; i < N+1; i++) {
                if (arr[start][i] == 1 && !check[i]) {
                    q.add(i);
                    check[i] = true;
                }
            }
        }
    }
}