阮小二买彩票

import java.util.Scanner;

public class Pailie {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        String str = n + "";
        String s[] = str.split("");
        
        int a[] = new int[s.length];
        for (int i = 0; i < s.length; i++) {
            a[i] = Integer.parseInt(s[i]);
        }
        a = sort(a);
        int m = s.length;
        int b[] = new int[s.length];
        
        f(a,m,b,"");
    }

    private static void f(int[] a, int m, int[] b, String se) {
        if(m == 0) {
            System.out.println(se);
        }
        for (int j = 0; j < a.length; j++) {        
            if(b[j] == 1) continue;
            b[j] = 1;
            f(a,m-1,b,se+a[j]);
            if(j<a.length-1 &&a[j]==a[j+1]) {
                b[j] = 0;
                j = j + h(a,j+1);
                continue;
            }
            b[j] = 0;
            continue;
        }
    }

    private static int h(int[] a, int j) {
        int w = 1;
        for (int i = j; i < a.length-1; i++) {
            if(a[j] == a[i+1]) {
                w++;
            }
        }
        return w;
    }

    private static int[] sort(int[] a) {
        for (int i = 0; i < a.length-1; i++) {
            for (int j = 0; j < a.length-1; j++) {
                if(a[j]>a[j+1]) {
                    int t = a[j];
                    a[j] = a[j+1];
                    a[j+1] = t;
                }
            }
        }
        return a;
    }
}

sort()：升序排列

h()：剔除重复代码