题解 | 打印日期

#include <iostream>
using namespace std;

bool is_run(int year){
    if(year%400==0)
        return true;
    if(year%100==0)
        return false;
    if(year%4==0)
        return true;
    return false;
}

int main() {
    int year,month,day,num;
    while (cin >> year >> num) { // 注意 while 处理多个 case
        int mon[12]={31,28,31,30,31,30,31,31,30,31,30,31};
        mon[1]+=is_run(year);
        for(int i=0;i<12;i++)
            if(num>mon[i])
                num-=mon[i];
            else{
                cout<<year<<'-'<<(i+1<10? "0":"")<<i+1<<'-'<<(num<10?"0":"")<<num<<endl;
                break;
            }            
    }
}
// 64 位输出请用 printf("%lld")