SGU - 115 - Calendar （基础题！）

SGU - 115

Calendar

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Description

First year of new millenium is gone away. In commemoration of it write a program that finds the name of the day of the week for any date in 2001.

Input

Input is a line with two positive integer numbers N and M, where N is a day number in month M. N and M is not more than 100.

Output

Write current number of the day of the week for given date (Monday ? number 1, ? , Sunday ? number 7) or phrase ?Impossible? if such date does not exist.

Sample Input

21 10

Sample Output

7

Source

看起来挺简单的一个题。。

但是我WA了3次，，哭%>_<%啊

要判断日期是否合法，不合法则输出Impossible，合法则输出所对应的星期几，而2001年第一天就是星期一，模7即可。。

AC代码：

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <cmath>
using namespace std;

int a[13] = {0,31,28,31,30,31,30,31,31,30,31,30,31};

int judge(int n, int m)     //判断日期是否合法
{
	if(n==1 || n==3 || n==5 || n==7 || n==8 || n==10 || n==12)
	{
		if(m<=31)return 0;
	}
	else if(n==4 || n==6 || n==9 || n==11)
	{
		if(m<=30)return 0;
	}
	else if(n==2)
	{
		if(m<=28)return 0;
	}
	else return 1;
}

int main()
{
	int n, m;
	int flag = 0, ans = 0;
	scanf("%d %d", &n, &m);
	if(judge(m, n))flag = 1;
	else
	{
		for(int i=1; i<m; i++)
		{
			ans += a[i];
		}
		ans += n;
	}
	if(flag)
	{
		printf("Impossible\n");
	}
	else
	{
		ans %= 7;
		if(ans == 0) ans = 7;
		printf("%d\n", ans);
	}
	return 0;
}