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

 1 class Solution {
 2 public:
 3     int numTrees(int n) {
 4         int *bst = new int[n+1];
 5         for(int i = 0 ; i < n+1; ++i)
 6             bst[i] = 0;
 7             
 8         bst[0] = 1;
 9         bst[1] = 1;
10         for(int i = 2; i <= n; ++i){
11             for(int j = 0 ; j < i; ++j){
12                 bst[i] += bst[j] * bst[i-j-1];
13             }
14         }
15         return bst[n];
16     }
17 };

动态规划？

转载于:https://www.cnblogs.com/nnoth/p/3744074.html