1069 The Black Hole of Numbers (20分)

//代码每次提交分数都不一样。。。原因不明，偶尔满分
#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <algorithm>
using namespace std;
const int Maxn = 2020;

bool cmp(int a,int b)
{
    return a > b;
}


int getdecrease(int n)
{
    int num[4];
    int ans = 0,t=0;
    while(n>0)
    {
        num[t++] = n%10;
        n/=10;
    }
    sort(num,num+4,cmp);
    for(int i = 0;i<4;i++)
    {
        ans = ans * 10 + num[i];
    }
    return ans;
}

int getincrease(int n)
{
    int num[4],ans = 0,t=0;
    while(n>0)
    {
        num[t++] = n%10;
        n/=10;
    }
    sort(num,num+4);
    for(int i = 0;i<4;i++)
    {
        ans = ans * 10 + num[i];
    }
    return ans;
}


int main()
{
    freopen("1.txt","r",stdin);
    int n;
    scanf("%d",&n);

    int a = getdecrease(n);
    int b = getincrease(n);

    while(1)
    {
        int c = a - b;
        printf("%04d - %04d = %04d\n",a,b,c);
        if(c == 6174 || c == 0)
            break;
        a = getdecrease(c);
        b = getincrease(c);
    }





    return 0;
}