Create 0894-all-possible-full-binary-trees.js

Author: aadil42

javascript/0894-all-possible-full-binary-trees.js

@@ -0,0 +1,45 @@
+/**
+ * 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)
+ * }
+ */
+/**
+ * DFS | Recursion
+ * Time O(2^n) | Space O(2^n)
+ * https://leetcode.com/problems/all-possible-full-binary-trees/
+ * @param {number} n
+ * @return {TreeNode[]}
+ */
+var allPossibleFBT = function(n) {
+    
+    // even number of nodes can't make a full binary tree.
+    if(!(n%2)) return [];
+
+    const dfs = (n) => {
+        if(n === 1) return [new TreeNode(0)];
+
+        const allPossibleTrees = [];
+        for(let i = 1; i < n; i+=2) {
+
+            const leftNumOfNodes = i;
+            const rightNumOfNodes = n - i - 1;
+
+            const leftTrees = dfs(leftNumOfNodes);
+            const rightTrees = dfs(rightNumOfNodes);
+
+            for(let i = 0; i < leftTrees.length; i++) {
+                for(let j = 0; j < rightTrees.length; j++) {
+                    const root = new TreeNode(0, leftTrees[i], rightTrees[j]);
+                    allPossibleTrees.push(root);
+                }
+            }
+        }
+
+        return allPossibleTrees;
+    }
+
+    return dfs(n);
+};