096.Unique-Binary-Search-Trees.cpp

class Solution {
public:
    int numTrees(int n) 
    {
        vector<int>dp(n+1);
        dp[0] = 1;
        dp[1] = 1;
        for (int i=2; i<=n; i++)
        {
            dp[i] = 0;
            for (int j=0; j<=i-1; j++)
                dp[i] += dp[j]*dp[i-1-j];
        }
        return dp[n];        
    }
};