[BOJ_15655] N과 M (6)

조합 사용 - 앞의 나왔던 문제들과 너무 유사하므로 설명을 따로 적지 않겠다.

 

 

package backtracking;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

public class BOJ_15655 {
    static int arr[];
    static int N,M;
    static StringBuilder sb;
    static boolean visited[];
    static int[] num;
    public static void main(String[] args) throws Exception {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer tk = new StringTokenizer(in.readLine()," ");

        N = Integer.parseInt(tk.nextToken());
        M = Integer.parseInt(tk.nextToken());

        tk = new StringTokenizer(in.readLine()," ");

        num = new int[N];
        visited = new boolean[N];
        for(int i = 0; i < N; i++){
            num[i] = Integer.parseInt(tk.nextToken());
        }

        arr = new int[M];

        Arrays.sort(num);
        sb = new StringBuilder();
        dfs(0,0);
        System.out.println(sb);
    }
    private static void dfs(int idx,int start) {
        if(idx == M){
            for (int i = 0; i < M; i++) {
                sb.append(arr[i] + " ");
            }
            sb.append('\n');
            return;
        }
        for(int i = start; i < N; i++){
            if(!visited[i]) {
                visited[i] = true;
                arr[idx] = num[i];
                dfs(idx + 1,i+1);
                visited[i] = false;
            }
        }
    }
}

 

15655번: N과 M (6)