Description

Submission

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) {
            for(int j = 1; j <= i; ++j) {
                dp[i] += dp[j - 1] * dp[i - j];
            }
        }
        return dp[n];
    }


};