[96 Unique Binary Search Trees] #leetcode

96_0801.java

public class Solution {
    public int numTrees(int n) {
        int[] dp = new int[n+1];
        
        dp[0] = 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];
    }
}