南阳oj 1103 区域赛系列一多边形划分

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区域赛系列一多边形划分
时间限制：1000 ms | 内存限制：65535 KB
难度：2
描述
Give you a convex（凸边形）, diagonal n-3 disjoint divided into n-2 triangles(直线), for different number of methods, such as n=5, there are 5 kinds of partition method, as shown in Figure

输入
The first line of the input is a n (1<=n<=1000), expressed n data set.
The next n lines each behavior an integer m (3<=m<=18), namely the convex edges.
输出
For each give m,, output how many classification methods.
example output: Case #a : b
样例输入
3
3
4
5
样例输出
Case #1 : 1
Case #2 : 2
Case #3 : 5
卡特兰数

#include<stdio.h>
void catl(long long int *p)
{
    p[0]=1;
    p[1]=1;
    for(int i=2; i<20; i++)
    {
        p[i]=p[i-1]*(4*i-2)/(i+1);
        //printf("p[%d]=p[%d]*%d/%d\n",i,i-1,(4*i-2),(i+1));
    }
}
int main()
{
    long long int a[20];
    catl(a);
    int n,t;
    while(~scanf("%d",&t))
    {
        for(int i=1; i<=t; i++)
        {
            scanf("%d",&n);
            printf("Case #%d : %lld\n",i,a[n-2]);
        }
    }
    return 0;
}