计算星期几

#include "stdio.h"
int week_day(int y,int m,int d)
{
 int result;
 int year=y%100;
 int c=y/100;

 if(m<3)
 {
  m+=12;
  y--;
 }
 result = year+(year/4)+(c/4)-2*c+(26*(m+1)/10)+d-1+7;
 return result%7;
}
void main()
{int result;
int y,m,d;
scanf("%d%d%d",&y,&m,&d);
result= week_day(y,m,d);
 printf("星期%d\n",result);
}