백준 15650 : N과 M (2) _자바 Java

https://www.acmicpc.net/problem/15650

15650번: N과 M (2)

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

public class Main {
	
	
	static int[] arr;	//출력하기 위한 값 저장
	static int N,M;
	
	public static void main(String[] args) throws IOException {
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String str = br.readLine();
		StringTokenizer st = new StringTokenizer(str , " ");
		N = Integer.parseInt(st.nextToken());	//1~N사이에
		M = Integer.parseInt(st.nextToken());	//M개씩

	
		arr = new int[M];
		
		bt(1,0);	
	
	}
	
	private static void bt(int a,int k) {
		
		if(k==M) {
			for(int val : arr) {
				System.out.print(val+" ");
			}
			System.out.println();
			return;
		}
		
		for(int i=a;i<=N;i++) {
			arr[k]=i;
			bt(i+1,k+1);
		}
		
	}
}