根据年月日计算星期几

根据年月日计算星期几，例如：

输入：1990 1 1  输出 monday

输入：2013 9 17 输出 tuesday

基姆.拉尔森 给出公式：

W=(d+1+2*m+3*(m+1)/5+y+(y>>2)-y/100+y/400)%7;

代码：

#include<iostream>
#include<cstdio>
using namespace std;
char *week[]={"sunday","monday","tuesday","wednesday","thursday","friday","saturday"};

void search(int y,int m,int d)
{
    if(m<3)
    {
        m+=12;
        --y;
    }
    int W=(d+1+2*m+3*(m+1)/5+y+(y>>2)-y/100+y/400)%7;
    cout<<week[W]<<endl;
}

int main()
{
    int y,m,d;
    while(~scanf("%d %d %d",&y,&m,&d))
        search(y,m,d);
    return 0;
}