ZOJ1256-What Day Is It?

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=256

还是耐心，注意细节。

#include<iostream>
#include<string>
#include<cstdio>
using namespace std;
const string weeks[]={"Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"};
const string months[]={"January","February","March","April","May","June","July","August","September","October","November","December"};
const int cnt[2][12]=
{
   31,28,31,30,31,30,31,31,30,31,30,31,
   31,29,31,30,31,30,31,31,30,31,30,31
};
int leapyear(int y)
{
    if(y%4==0&&y%100!=0||y%400==0)
       return 1;
    return 0;
}
int DayOfWeek(int M,int D,int Y)
{
    if(M==1||M==2)
    {
        M+=12;
        --Y;
    }
    if(Y<1752||Y==1752&&M<9||Y==1752&&M==9&&D<3)
       return(D+2*M+3*(M+1)/5+Y+Y/4+5)%7;
    else
       return (D+2*M+3*(M+1)/5+Y+Y/4-Y/100+Y/400)%7;
}
bool Check(int m,int d,int y)
{
    if(!(m>=1&&m<13)) 
       return false;
    if(!(d>=1&&d<=cnt[leapyear(y)][m-1])) 
       return false;
    if(y==1752&&m==9&&d>2&&d<14) 
       return false;
    return true;
}
int main(void)
{
    int m,d,y;
    while(cin>>m>>d>>y,m+d+y)
    {
        if(Check(m,d,y))
           printf("%s %d, %d is a %s\n",months[m-1].c_str(),d,y,weeks[DayOfWeek(m,d,y)].c_str());
        else
           printf("%d/%d/%d is an invalid date.\n",m,d,y);
    }
    return 0;
}