Add solution #95

Author: JoshCrozier

README.md

@@ -78,6 +78,7 @@
 90|[Subsets II](./0090-subsets-ii.js)|Medium|
 93|[Restore IP Addresses](./0093-restore-ip-addresses.js)|Medium|
 94|[Binary Tree Inorder Traversal](./0094-binary-tree-inorder-traversal.js)|Easy|
+95|[Unique Binary Search Trees II](./0095-unique-binary-search-trees-ii.js)|Medium|
 98|[Validate Binary Search Tree](./0098-validate-binary-search-tree.js)|Medium|
 100|[Same Tree](./0100-same-tree.js)|Easy|
 101|[Symmetric Tree](./0101-symmetric-tree.js)|Easy|

solutions/0095-unique-binary-search-trees-ii.js

@@ -0,0 +1,37 @@
+/**
+ * 95. Unique Binary Search Trees II
+ * https://leetcode.com/problems/unique-binary-search-trees-ii/
+ * Difficulty: Medium
+ *
+ * Given an integer n, return all the structurally unique BST's (binary search
+ * trees), which has exactly n nodes of unique values from 1 to n. Return the
+ * answer in any order.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {number} n
+ * @return {TreeNode[]}
+ */
+var generateTrees = function(n) {
+  return backtrack(n);
+};
+
+function backtrack(n, j = 1, k = n, result = []) {
+  for (let index = j; index <= k; index++) {
+    for (const left of backtrack(n, j, index - 1)) {
+      for (const right of backtrack(n, index + 1, k)) {
+        result.push({ val: index, left, right });
+      }
+    }
+  }
+
+  return n ? result.length ? result : [null] : [];
+}