PAT甲级1069 The Black Hole of Numbers (20 分)

字符串处理

#include<iostream>
#include<algorithm>
using namespace std;

char cmp(char a,char b){
    
    return a>b;}
int main()
{
    
    
    string s;
    cin>>s;
    s.insert(0,4-s.size(),'0');
    do{
    
    
        string s1=s,s2=s;
        sort(s1.begin(),s1.end(),cmp);
        sort(s2.begin(),s2.end());
        int a1=stoi(s1),a2=stoi(s2);
        s=to_string(a1-a2);
        s.insert(0,4-s.size(),'0');
        cout<<s1<<" - "<<s2<<" = "<<s<<endl;
    }while(s!="0000" && s!="6174");
    return 0;
}