蔡勒公式 知道年月日求星期几——pku3047

#include <stdio.h>
int main()
{
    int year,month,day;
    while(scanf("%d%d%d",&year,&month,&day)!=EOF)
    {
        if ( month < 3 ) 
        {
            year -= 1;
            month += 12;
        }
        char b[7][10] = {"sunday","monday","tuesday","wednesday","thursday","friday","saturday"};
        int c = year/100, y = year - 100 * c;
        int w = c/4 - 2*c +y+y/4 +(26 * (month + 1)/10 ) + day - 1;
        w = (w % 7+7)%7;//注意不然如2003 3 1会错，w可能为-22
        printf("%s\n",b[w]);
    }
}