Leetcode 96 Submission Details

Given n, how many structurally unique BST's (binary search trees) that store values 1...n?

For example,
Given n = 3, there are a total of 5 unique BST's.

   1         3     3      2      1
    \       /     /      / \      \
     3     2     1      1   3      2
    /     /       \                 \
   2     1         2                 3

Solution 1: best way to use DP.

 public class Solution {  
   public int numTrees(int n) {  
     int[] dp=new int[n+1];  
     for (int i=0; i<=n; i++) {  
       if (i==0) dp[i]=1;  
       else {  
         for (int j=0; j<i; j++) dp[i]+=dp[j]*dp[i-1-j];  
       }  
     }  
     return dp[n];  
   }  
 }