P1157 组合的输出(dfs)

import java.util.Scanner;

public class P1157 {
	static int T,n,r;
	static int[] arr; 
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		n = sc.nextInt();
		r = sc.nextInt();
		arr = new int[r+1];
		dfs(1);
	}
	
	private static void dfs(int step) {
		if(step>r) {
			for(int i=1;i<=r;i++) {
				System.out.printf("%3d",arr[i]);
			}
			System.out.println();
			return;
		}
		for(int i=arr[step-1]+1;i<=n;i++) {
			arr[step] = i;
			dfs(step+1);
		}
		
	}
}