uva 10007 Count the Trees

http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=948

卡特兰数*n！

 import java.math.BigInteger;
 import java.util.*;
 public class Main {
       public static void main(String[]args)
       {
           Scanner cin=new Scanner(System.in);
           BigInteger []a=new BigInteger[1000];
           a[0]=BigInteger.valueOf(1);
           for(int i=1; i<=300; i++)
           {
               int m=(4*i-2);
               a[i]=a[i-1].multiply(BigInteger.valueOf(m));
               a[i]=a[i].divide(BigInteger.valueOf(i+1));
           }
           int n;
           while(cin.hasNext())
           {
               n=cin.nextInt();
               if(n==0) break;
               BigInteger ans=BigInteger.valueOf(1);
               for(int i=1; i<=n; i++)
               {
                   ans=ans.multiply(BigInteger.valueOf(i));
               }
               ans=ans.multiply(a[n]);
               System.out.println(ans);
           }
       }
 }