蓝桥杯算法提高VIP-阮小二买彩票-题解（Java代码）

解题思路:

注意事项:

参考代码:

import java.math.BigInteger;

import java.util.ArrayList;

import java.util.Collections;

import java.util.HashSet;

import java.util.List;

import java.util.Scanner;

public class Main {

static HashSet<Integer> set = new HashSet<Integer>();

static String str1="";

public static void main(String[] args) {

Scanner scanner=new Scanner(System.in);

String str=scanner.next();

int n=str.length();

int[] a=new int[n];

for(int i=0;i<n;i++) {

a[i]=Integer.parseInt(""+str.charAt(i));

}

pd(a,0);

List<Integer> list = new ArrayList<>(set);

Collections.sort(list);

for(int i=0;i<list.size();i++) {

if(a.length==1)

System.out.printf("%d\n",list.get(i));

else if(a.length==2)

System.out.printf("%02d\n",list.get(i));

else if(a.length==3)

System.out.printf("%03d\n",list.get(i));

else if(a.length==4)

System.out.printf("%04d\n",list.get(i));

else if(a.length==5)

System.out.printf("%05d\n",list.get(i));

else

System.out.printf("%06d\n",list.get(i));

}

}

private static void pd(int[] a, int m) {

// TODO Auto-generated method stub

if(m==a.length) {

str1="";

for(int i=0;i<a.length;i++) {

str1=a[i]+str1;

}

set.add(Integer.parseInt(str1));

return;

}

for(int i=m;i<a.length;i++) {

int t=a[i];

a[i]=a[m];

a[m]=t;

pd(a,m+1);

t=a[i];

a[i]=a[m];

a[m]=t;

}

}

}