[leetcode][***] Unique Tree

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

This is a DP problem.

In Order, n = 0, result = 1:

int numTrees(int n) {
      int table[n+1];
      memset(table, 0, sizeof(int)*(n+1));
      for(int i = 0; i <= n; ++i){
          if(i < 2) table[i] = 1;
          else{
              for(int j = 0; j < i; ++j){
                  table[i] += table[j]*table[i-j-1];
              }
          }
      }
      return table[n];
    }