蓝桥杯练习—计算某年某月某日为星期几

以上为日期计算公式

 #define _CRT_SECURE_NO_WARNINGS 1 
#include<iostream>
#include<string>
using namespace std;

int whatday(int y, int m, int d)
{
	int ans = 0;
	for (int i = 1; i < y; i++)
	{
		if ((i % 4 == 0 && i % 100 != 0) || i % 400 == 0)
		{
			ans += 366 % 7;
			ans %= 7;
		}
		else
		{
			ans += 365 % 7;
			ans %= 7;
		}
	}
	for (int i = 1; i < m; i++)
	{
		if (i == 1 || i == 3 || i == 5 || i == 7 || i == 8 || i == 10 || i == 12)
		{
			ans += 31 % 7;
			ans %= 7;
		}
		else if (i == 4 || i == 6 || i == 9 || i == 11)
		{
			ans += 30 % 7;
			ans %= 7;
		}
		else if ((y % 100 != 0 && y % 4 == 0) || y % 400 == 0)
		{
			ans += 29 % 7;
			ans %= 7;
		}
		else
		{
			ans += 28 % 7;
			ans %= 7;
		}
	}
	ans += (d - 1) % 7;
	ans %= 7;
	return ans;
}

string weekday[7] = { "Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday" };

int main()
{
	int y, m, d;
	cin >> y >> m >> d;
	cout << weekday[whatday(y, m, d)] << endl;
	return 0;
}