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Java-based LeetCode algorithm problem solutions, regularly updated

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package g0001_0100.s0096_unique_binary_search_trees;

// #Medium #Top_100_Liked_Questions #Dynamic_Programming #Math #Tree #Binary_Tree
// #Binary_Search_Tree #Dynamic_Programming_I_Day_11 #Big_O_Time_O(n)_Space_O(1)
// #2022_06_21_Time_0_ms_(100.00%)_Space_40.4_MB_(72.43%)

/**
 * 96 - Unique Binary Search Trees\.
 *
 * Medium
 *
 * Given an integer `n`, return _the number of structurally unique **BST'**s (binary search trees) which has exactly_ `n` _nodes of unique values from_ `1` _to_ `n`.
 *
 * **Example 1:**
 *
 * ![](https://assets.leetcode.com/uploads/2021/01/18/uniquebstn3.jpg)
 *
 * **Input:** n = 3
 *
 * **Output:** 5 
 *
 * **Example 2:**
 *
 * **Input:** n = 1
 *
 * **Output:** 1 
 *
 * **Constraints:**
 *
 * *   `1 <= n <= 19`
**/
public class Solution {
    public int numTrees(int n) {
        long result = 1;
        for (int i = 0; i < n; i++) {
            result *= 2L * n - i;
            result /= i + 1;
        }
        result /= n + 1;
        return (int) result;
    }
}