96. Unique Binary Search Trees 动态规划

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

分析：

参见leetcode上的分析Leetcode

代码：

class Solution {

public:

    int numTrees(int n) {

        vector<int>G(n+1,0);

        // for(int t=1;t<G.size();++t)

        G[0]=1;

        G[1]=1;

        for(int i=2;i<=n;++i)

        for(int j=0;j<i;++j)

        G[i]=G[i]+G[j]*G[i-j-1];

         

         return G
;

        

    }

};