[백준 | Java Silver III] (#15651) N과 M (3)

문제

https://www.acmicpc.net/problem/15651

 

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첫번째 코드 - 시간 초과

package week13.baek.august06;

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

public class S15651 {
    static int n, m;

    public static void dfs(int depth, String s){
        if(depth == m){
            System.out.println(s);
            return;
        }

        for (int i = 0; i < n; i++) {
                dfs(depth+1, s + " " + (i+1));
        }
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());
        n = Integer.parseInt(st.nextToken());
        m = Integer.parseInt(st.nextToken());

        for (int i = 0; i < n; i++) {
            dfs(1, String.valueOf(i+1));
        }

    }
}

 

 

최종 코드 - StringBuilder 사용

package week13.baek.august06;

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

public class S15651 {
    static int n, m;

    public static void dfs(int depth, String s){
        if(depth == m){
            System.out.println(s);
            return;
        }

        for (int i = 0; i < n; i++) {
                dfs(depth+1, s + " " + (i+1));
        }
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());
        n = Integer.parseInt(st.nextToken());
        m = Integer.parseInt(st.nextToken());

        for (int i = 0; i < n; i++) {
            dfs(1, String.valueOf(i+1));
        }

    }
}