617. Merge Two Binary Trees

nutandevjoshi · nutandevjoshi · commit 0facc216874f · 2022-11-19T16:06:27.000+05:30
diff --git a/javascript/617-Merge-Two-Binary-Trees.js b/javascript/617-Merge-Two-Binary-Trees.js
@@ -0,0 +1,20 @@
+/**
+ * @param {TreeNode} root1
+ * @param {TreeNode} root2
+ * @return {TreeNode}
+ * Time complexity = O(n+m) 
+ */
+ var mergeTrees = function(root1, root2) {
+    // Base case to return null as result of having both root1, root2 null
+    if(!root1 && !root2) {
+        return null;
+    }
+
+    const val1 = root1 ? root1.val : 0;
+    const val2 = root2 ? root2.val : 0;
+    
+    const root = new TreeNode(val1+val2);
+    root.left = mergeTrees(root1 ? root1.left : null, root2 ? root2.left: null);
+    root.right = mergeTrees(root1 ? root1.right : null , root2 ? root2.right: null);
+    return root;
+};
