hdu Game of Connections

卡特兰数 递推公式：h(n)=h(n-1)*(4*n-2)/(n+1);

 1 import java.math.BigInteger;

 2 import java.util.Scanner;

 3 

 4 public class Main {

 5 

 6     public static void main(String args[]) {

 7         Scanner cin = new Scanner(System.in);

 8         BigInteger[] c = new BigInteger[101];

 9         c[1] = BigInteger.valueOf(1);

10         c[2] = BigInteger.valueOf(2);

11         for (int i = 3; i <= 100; i++) {

12             BigInteger x1 = BigInteger.valueOf(4*i-2);

13             BigInteger x2 = BigInteger.valueOf(i+1);

14             c[i]=c[i-1].multiply(x1).divide(x2);

15         }

16     

17         while (cin.hasNext()) {

18             int N = cin.nextInt();

19             if (N==-1)

20                 break;

21             else

22                 System.out.println(c[N]);

23         }

24     }

25 }

View Code