题解 | #计算日期到天数转换#

#include <iostream>
using namespace std;
#define isyear(x) ((x%4 == 0)&&(x%100 !=0)||(x%400 == 0))


    bool Check(int year,int month,int day)
    {
        static int MonthDay[13][2]={0,0,31,31,28,29,31,31,30,30,31,31,30,30,31,31,31,31,30,30,31,31,30,30,31,31};
        if(year<1000||year>9999)
        return false;
        if(month<1||month>12)
        return false;
        if(day<1||day>MonthDay[month][isyear(year)])
        return false;

        return true;
    }

int GetDay(int year,int month,int day)
{
     static int Day[13][2]={0,0 ,31,31, 59,60, 90,91, 120,121, 151,152, 181,182, 212,213, 243,244, 273,274, 304,305, 334,335, 365,366};
    if(!Check(year,month,day))
    return -1;

    int daysum=Day[month-1][isyear(year)]+day;
    return daysum;

}

int main() {
   
    int y,m,d;
    cin>>y>>m>>d;
    int day=GetDay(y,m,d);
    if(day == -1)
    {
        cout<<"日期非法"<<endl;
    }
    else {
    cout<<day<<endl;
    }
    return 0;
}