lintcode 中等题：unique Binary Search Tree 不同的二叉查找树

public class Solution {
    /**
     * @paramn n: An integer
     * @return: An integer
     */
    public int numTrees(int n) {
        // write your code here
        int[] count = new int[n + 1];
        if( n==0 )
            return 1;
        count[0] = 1;
        count[1] = 1;
 
        for (int i = 2; i <= n; i++) {
            for (int j = 0; j <= i - 1; j++) {
                count[i] = count[i] + count[j] * count[i - j - 1];
            }
        }
        return count[n];
    }
}