递归实现指数型枚举 Java

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

public class Main {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		int n = Integer.parseInt(st.nextToken());
		for (int i = 0; i < (1 << n); i++) {  // 1<<n就是2的n次方，即遍历0 ~ 2的n次方-1
			for (int j = n - 1, k = 1; j >= 0; j--, k++) { // j--是因为i>>j需要从左到右比较
				if (((i >> j) & 1 )== 1) System.out.print(k + " ");
			}
			System.out.println();
		}
	}
}

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