题解 | #日期差值#

#include <iostream>
using namespace std;
int M[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
bool isrun(int y){
    if(y%400==0||(y%4==0&&y%100!=0)) return true;
    return false;
}
void add(int& y,int& m,int& d){
    if(isrun(y)) M[2]=29;else M[2]=28;
    d++;if(d>M[m]) {d=1;m++;if(m>12){m=1;y++;}}
    
}
int main() {
    string a, b;int ans=0;
   cin >> a >> b;if(a>b) swap(a,b);
        int y1=stoi(a.substr(0,4));
        int m1=stoi(a.substr(4,2)); int d1=stoi(a.substr(6,2));
          int y2=stoi(b.substr(0,4));
        int m2=stoi(b.substr(4,2)); int d2=stoi(b.substr(6,2));
        while(y1!=y2||m1!=m2||d1!=d2){
            add(y1,m1,d1);ans++;
        }
        
        cout<<ans+1;
    
}
// 64 位输出请用 printf("%lld")