96.Unique-Binary-Search-Trees.cpp

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