区域赛系列一多边形划分
1000 ms | 内存限制： 65535
难度：2
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
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
3345
样例输出
Case #1 : 1
Case #2 : 2
Case #3 : 5
//题意：
给你一个有 n条边的凸边形，让你用n-3条直线见他分成n-2个三角形，问有几种分法。
#include<stdio.h>
#include<string.h>
int main()
{
int a[20];
int t,T=1,n,i,j,b;
a[2]=a[3]=1;
for(i=3;i<20;i++)
{
a[i]=0;
b=i-1;
for(j=2;j<i;j++)
{
a[i]+=a[j]*a[b];
b--;
}
}
scanf("%d",&t);
while(t--)
{
scanf("%d",&n);
printf("Case #%d : %d\n",T++,a[n]);
}
return 0;
}
