打卡

#include <iostream>
using namespace std;
int main() {
    int year,month;
    cin>>year>>month;
    
    int days[]={31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    bool a=false;
    if ((year%400==0)||(year%4==0&&year%100!=0)){
        a=true;
    }
    if(month==2&&a) {
        cout<<29<<endl;
    }else{
        cout<<days[month-1]<<endl;
    }    
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int a;
    int b;
    cin>>a>>b;
    int c[12]={31,29,31,30,31,30,31,31,30,31,30,31},d[12]={31,28,31,30,31,30,31,31,30,31,30,31};
    if((a%100!=0&&a%4==0)||a%400==0)cout<<c[b-1];
    else cout<<d[b-1];
}

C++ :

#include <bits/stdc++.h>
using namespace std;
int main() {
    int year, month;
    cin >> year >> month;
    if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 ||
        month == 10 || month == 12) {
        cout << 31;
    } else if (month == 4 || month == 6 || month == 9 || month == 11) {
        cout << 30;
    } else if (month == 2) {
        if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
            cout << 29;
        } else {
            cout << 28;
        }
    }
    return 0;
}