题目描述

java递归

样例

import java.util.Scanner;

public class Main {
    static final int N = 15;
    static int n;
    static int[] st = new int[N + 1]; // 数组大小增加1以适应从1开始索引

    public static void dfs(int u) {
        if (u > n) {
            for (int i = 1; i <= n; i++) {
                if (st[i] == 1) {
                    System.out.print(i + " ");
                }
            }
            System.out.println();
            return;
        }

        st[u] = 1;
        dfs(u + 1);
        st[u] = 0;

        st[u] = 2;
        dfs(u + 1);
        st[u] = 0;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        n = scanner.nextInt();
        dfs(1);
        scanner.close(); // 关闭scanner对象
    }
}