ZOJ 3785 What day is that day? （找规律）

1、http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=3785

2、题目：

It's Saturday today, what day is it after 1¹ + 2² + 3³ + ... + N^N days?

Input

There are multiple test cases. The first line of input contains an integer T indicating the number of test cases. For each test case:

There is only one line containing one integer N (1 <= N <= 1000000000).

Output

For each test case, output one string indicating the day of week.

Sample Input

2
1
2

Sample Output

Sunday
Thursday

Hint

A week consists of Sunday, Monday, Tuesday, Wednesday, Thursday, Friday and Saturday.

3、思路：

打表i的i次方%7后的值，就可以发现42一循环

然后用公式计算出结果

int ans=(n/42%7*(s[42]%7)%7+s[n%42]%7)%7;

最后输出

str[ans]

即可

4、AC代码：

#include<stdio.h>
int s[45];
char str[7][10]={"Saturday","Sunday","Monday","Tuesday","Wednesday","Thursday","Friday"};
int main()
{s[0]=0;for(int i=1;i<=44;i++){int flag=i%7;int ans=1;for(int j=1;j<=i;j++)ans=(ans*flag)%7;s[i]=ans;}for(int i=1;i<=44;i++){s[i]+=s[i-1];}int t;while(scanf("%d",&t)!=EOF)while(t--){int n;scanf("%d",&n);int ans=(n/42%7*(s[42]%7)%7+s[n%42]%7)%7;printf("%s\n",str[ans]);}
}