太复杂了，建议先判断是否超过0点，在运用%运算求分钟，除法求小时！！！！
by zjm20130703 @ 2023-08-09 21:16:37
###### 提供简洁思路
```c
#include<iostream>
using namespace std;
int main() {
int s, v;
cin >> s >> v;
int allMin = s / v + 10 + (s % v != 0 ? 1 : 0);
int remain = allMin <= 480 ? 480 - allMin : 1440 + 480 - allMin;
int hour = remain / 60;
int min = remain % 60;
string hourStr = to_string(hour);
string minStr = to_string(min);
string res = (hour < 10 ? "0" + hourStr : hourStr) + ":" + (min < 10 ? "0" + minStr : minStr);
cout << res;
return 0;
}
```
by yuanzhisong @ 2023-08-23 11:37:16