Create 0095-unique-binary-search-trees-ii.js

Author: aadil42

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

@@ -0,0 +1,47 @@
+/**
+ * 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)
+ * }
+ */
+/**
+ * Recursion
+ * Time O(4^n) | Space O(n)
+ * https://leetcode.com/problems/unique-binary-search-trees-ii/ 
+ * @param {number} n
+ * @return {TreeNode[]}
+ */
+var generateTrees = function(n) {
+
+    const dfs = (start, end) => {
+
+        const result = [];
+
+        if(start === end) {
+            result.push(new TreeNode(start));
+            return result;
+        };
+        if(start > end)  {
+            result.push(null);
+            return result;
+        };
+
+        for(let i = start; i < end + 1; i++) {
+            const leftSubTrees = dfs(start, i - 1);
+            const rightSubTrees = dfs(i + 1 , end);
+
+            leftSubTrees.forEach((leftSubTree) => {
+                rightSubTrees.forEach((rightSubTree) => {
+                    const root = new TreeNode(i, leftSubTree, rightSubTree); 
+                    result.push(root);
+                });
+            });            
+        }
+
+        return result;
+    }
+
+    return dfs(1, n);
+};