蔡勒公式

这个公式使用于1572年10月15日之后

#include <stdio.h>int main(){    int year,month,day;    char weekday[7][10]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};    while(scanf("%d%d%d",&year,&month,&day)!=EOF)    {        int i,j,k;        int c=year/100;        int y=year-c*100;        int week=int(c/4)-2*c+int(y+y/4)+int(13*(month+1)/5)+day-1;        while(week<0)        {            week+=7;        }        week%=7;        printf("%s\n",weekday[week]);    }    return 0;}