PAT甲级 1006. Sign In and Sign Out (25)

#include <iostream>
#include <cstring>
#include <string>
using namespace std;

int main(){
string mins, maxs, str;
string minT = "23:59:59";
string maxT = "00:00:00";
string tmp_in, tmp_out;
int num, i;

cin >> num;
for(i = 0; i < num; i++){
cin >> str >> tmp_in >> tmp_out;
if(tmp_in <= minT){
mins = str;
minT= tmp_in;
}
if(tmp_out >= maxT){
maxs = str;
maxT = tmp_out;
}
}
cout << mins << " " << maxs << endl;
return 0;
}