HDU - 5391（打表找规律）

Tina Town is a friendly place. People there care about each other.

Tina has a ball called zball. Zball is magic. It grows larger every day. On the first day, it becomes 1 time as large as its original size. On the second day,it will become 2 times as large as the size on the first day. On the n-th day,it will become n

times as large as the size on the (n-1)-th day. Tina want to know its size on the (n-1)-th day modulo n.

Input The first line of input contains an integer T, representing the number of cases.

The following T lines, each line contains an integer n, according to the description.
T≤105,2≤n≤109
Output For each test case, output an integer representing the answer. Sample Input

2
3
10

Sample Output

2
0

题意：有一个球初始大小为1，在第n天的时候回变成第n-1天的n倍，问第n天的球的大小取余n是多少？

这题感觉无从下手，题目求的是第n天的球的大小取余n的值，但是我们只要打个表就会发现，这个值跟n有关，若n是素数，那么答案就是n-1，否则就是0。

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define inf 0x3fffffff
using namespace std;
typedef long long LL;
const int N=1e9+1;
unsigned long long a[1000];
int main()
{
    //打表找规律
//    a[1]=1,a[2]=2;
//    for(int i=3;i<=21;i++)
//    {
//        a[i]=i*a[i-1];
//        printf("%llu %d %llu\n",a[i-1],i,a[i-1]%i);
//    }
    int t,n;
    bool flag;
    scanf("%d",&t);
    while(t--)
    {
        flag=true;
        scanf("%d",&n);
        if(n==2) printf("1\n");
        else if(n==3||n==4) printf("2\n");
        else
        {
            for(int i=2;i*i<=n;i++)
                if(n%i==0)
                {
                    printf("0\n");
                    flag=false;
                    break;
                }
            if(flag) printf("%d\n",n-1);
        }
    }
}