杭电acm2133 今天星期几

#include  
#include<string.h>  
using namespace std;  
int a[13] = {0,31,29,31,30,31,30,31,31,30,31,30,31};  
int b[13] = {0,31,28,31,30,31,30,31,31,30,31,30,31};  
char s[8][10] = {"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};  
bool IsRunNian(int year)  
{  
    if((year%4==0 && year%100!=0) || year%400==0)  
        return true;  
    return false;  
}  
int main()  
{  
    int year,month,day;  
    while(cin >> year >> month >> day)  
    {  
        if(IsRunNian(year))  
        {  
            if(day > a[month] || month == 0 || day == 0)  
            {  
                cout << "illegal" << endl;  
                continue;  
            }  
        }  
        else  
        {  
            if(day > b[month] || month == 0 || day == 0)  
            {  
                cout << "illegal" << endl;  
                continue;  
            }  
        }  
        int sum = 0;  
        for(int i = 1; i < year; ++i)  
        {  
            if(IsRunNian(i))  
                sum += 366;  
            else  
                sum += 365;  
            sum %= 7;  
        }  
        for(int i = 0; i < month; ++i)  
        {  
            if(IsRunNian(year))  
                sum += a[i];  
            else  
                sum += b[i];  
            sum %= 7;  
        }  

        sum += day;  
        sum %= 7;  
        cout << s[sum] << endl;  
    }  

    return 0;  
}