将字符串转换为数字，暴力模拟

#include<iostream>
#include<cstring>
#include<algorithm>
#define int long long
using namespace std;
string s1,s2;
int n;
signed main(){
    cin>>n;
    getchar();

    while(n--){
        int time=0;
        getline(cin,s1),getline(cin,s2);
        int time1=0,time2=0;
        if(s1.size()<=20) time1=((s1[9]*10+s1[10])*3600+(s1[12]*10+s1[13])*60+(s1[15]*10+s1[16]))-((s1[0]*10+s1[1])*3600+(s1[3]*10+s1[4])*60+(s1[6]*10+s1[7]));
        else time1=((s1[9]*10+s1[10])*3600+(s1[12]*10+s1[13])*60+(s1[15]*10+s1[16])+(s1[20]-'0')*3600*24)-((s1[0]*10+s1[1])*3600+(s1[3]*10+s1[4])*60+(s1[6]*10+s1[7]));

        if(s2.size()<=20) time2=((s2[9]*10+s2[10])*3600+(s2[12]*10+s2[13])*60+(s2[15]*10+s2[16]))-((s2[0]*10+s2[1])*3600+(s2[3]*10+s2[4])*60+(s2[6]*10+s2[7]));
        else time2=((s2[9]*10+s2[10])*3600+(s2[12]*10+s2[13])*60+(s2[15]*10+s2[16])+(s2[20]-'0')*3600*24)-((s2[0]*10+s2[1])*3600+(s2[3]*10+s2[4])*60+(s2[6]*10+s2[7]));

        int hour,minute,second=0;
        time=(time2+time1)/2;
        hour=time/3600;
        minute=(time%3600)/60;
        second=time%60;

        if(hour<10)cout<<0;
        cout<<hour<<':';
        if(minute<10)cout<<0;
        cout<<minute<<':';
        if(second<10)cout<<0;
        cout<<second<<endl;
    }

    return 0;
}