数字黑洞题解

学生版：

#include<bits/stdc++.h>
using namespace std;
int change(int num) {
    int a=num/100;
    int b=num/10%10;
    int c=num%10;
    int arr[3]={a,b,c};
    sort(arr,arr+3);
    int min_num=arr[0]*100+arr[1]*10+arr[2];
    int max_num=arr[2]*100+arr[1]*10+arr[0];
    return max_num-min_num;
}
int main()
{
    int n;
    cin>>n;
    int count=0;
    while(n!=495) {
        n=change(n);
        count++;
    }
    cout<<count<<endl;
    return 0;
}

老师版：

#include<bits/stdc++.h>
using namespace std;
int change(int num) {
    int a=num/100;
    int b=num/10%10;//b=num%100/10
    int c=num%10;
    int arr[3]={a,b,c};
    sort(arr,arr+3);//从小到大：sort(arr,arr+3,greater())从大到小
    int min_num=arr[0]*100+arr[1]*10+arr[2];
    int max_num=arr[2]*100+arr[1]*10+arr[0];
    return max_num-min_num;
}
int main()
{
    int n;
    cin>>n;
    int count=0;
    while(n!=495) {
        n=change(n);
        count++;
    }
    cout<<count<<endl;
    return 0;
}