题解 | #不同的二叉搜索树#动态规划

class Solution {
  public:
    /**
     *
     * @param n int整型
     * @return int整型
     */
    int numTrees(int n) {
        vector<int> dp(n + 1);
        dp[0] = 1;
        dp[1] = 1;
        dp[2] = 2;
        for (int i = 3; i <= n; i++) {
            for (int j = 1; j <= i; j++) {
                dp[i] += dp[j - 1] * dp[i - j];
            }
        }
        return dp[n];
    }
};