POJ 3047 Bovine Birthday 给出年月日求星期 蔡勒公式

#include <cstdio>
#include <cstring>
using namespace std;
char a[7][10] = {"sunday", "monday", "tuesday", "wednesday", "thursday", "friday", "saturday"};
int main()
{
	int y, m, d;
	while(scanf("%d %d %d", &y, &m, &d) != EOF)
	{	
		if(m < 3)
		{
			y--;
			m += 12;
		}
		int c = y / 100;
		y = y % 100;
		int w = y + y/4 + c/4 - 2*c + 26 * (m+1)/10 + d - 1;
		printf("%s\n", a[(w%7+7)%7]);
	}
	return 0;
}