LeetCode-in-All
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:
Input: n = 3
Output: 5
Example 2:
Input: n = 1
Output: 1
Constraints:
1 <= n <= 19
Solution
/**
* @param {number} n
* @return {number}
*/
var numTrees = function (n) {
let result = 1
for (let i = 0; i < n; i++) {
result *= 2 * n - i
result /= i + 1
}
result /= n + 1
return Math.floor(result)
};
export { numTrees }