@[chenqile](/user/953664) 半夜出发？
by happypigIG @ 2023-12-19 20:42:28
??@[PengDave](https://www.luogu.com.cn/user/1048193)怎么变成50分了
by chenqile @ 2023-12-19 21:04:20
@[chenqile](/user/953664) 要注意前一天出发的情况
```cpp
#include <cstdio>
int main(){
long long s, v;
scanf("%lld %lld", &s, &v);
int k = (s%v==0)?s/v:s/v+1;
int hm=8*60+24*60-k-10;//24*60是前一天的小时数
if(hm>=24*60) hm-=24*60;//如果不是前一天，就减了前一天的小时数
if(hm/60<10){
printf("0%d:", hm/60);
}else{
printf("%d:",hm/60);
}
if(hm%60<=9) printf("0%d", hm%60);
else printf("%d", hm%60);
return 0;
}
```
by PengDave @ 2023-12-19 21:05:18
@[chenqile](/user/953664) 代码发错了
by PengDave @ 2023-12-19 21:06:07
考虑前一天出发的情况
```cpp
#include <bits/stdc++.h>
using namespace std;
int s,v;
int main(){
scanf("%d%d",&s,&v);
int k = ceil((double)s / v) + 10;
int t = 480 + 1440;
t -= k;
if (t >= 1440) t -= 1440;
if (t / 60 < 10) printf("0");
printf("%d:",t / 60);
if (t % 60 < 10) printf("0");
printf("%d",t % 60);
return 0;
}
```
by I_Love_DS @ 2023-12-19 21:24:26
补充说明：以下为有注释
```cpp
#include <bits/stdc++.h>
using namespace std;
int s,v;
int main(){
scanf("%d%d",&s,&v);//输入
int k = ceil((double)s / v) + 10;//求去学校所需时间
int t = 480 + 1440;//出发时间
t -= k;//减
if (t >= 1440) t -= 1440;//如果不在前一天，-1天
if (t / 60 < 10) printf("0");//前导0
printf("%d:",t / 60);
if (t % 60 < 10) printf("0");//前导0
printf("%d",t % 60);
//结束
return 0;
}
```
by I_Love_DS @ 2023-12-19 21:31:45