solves merge two binary trees

Author: anishLearnsToCode

README.md

@@ -160,8 +160,8 @@
 | 599 | [Minimum Index Sum of 2 Lists](https://leetcode.com/problems/minimum-index-sum-of-two-lists) | [![Java](assets/java.png)](src/MinimumIndexSumOfTwoLists.java) [![Python](assets/python.png)](python/minimum_index_sum_of_two_lists.py) |
 | 604 | 🔒 [Design Compressed String Iterator](https://leetcode.com/problems/design-compressed-string-iterator) | |
 | 605 | [Can Place Flowers](https://leetcode.com/problems/can-place-flowers) | [![Java](assets/java.png)](src/CanPlaceFlowers.java) [![Python](assets/python.png)](python/can_place_flowers.py) |
-| 606 | [Construct String from Binary Tree](https://leetcode.com/problems/construct-string-from-binary-tree) | [![Java](assets/java.png)](src/ConstructStringFromBinaryTree.java) [![Python](assets/python.png)](python/construct_string_from_binary_tree.py)|
-| 617 | [Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees) | |
+| 606 | [Construct String from Binary Tree](https://leetcode.com/problems/construct-string-from-binary-tree) | [![Java](assets/java.png)](src/ConstructStringFromBinaryTree.java) [![Python](assets/python.png)](python/construct_string_from_binary_tree.py) |
+| 617 | [Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees) | [![Java](assets/java.png)](src/MergeTwoBinaryTrees.java) [![Python](assets/python.png)](python/merge_two_binary_trees.py) |
 | 624 | [Maximum Distance in Arrays](https://leetcode.com/problems/maximum-distance-in-arrays) | |
 | 628 | [Maximum Product of Three Numbers](https://leetcode.com/problems/maximum-product-of-three-numbers) | |
 | 633 | [Sum Square Numbers](https://leetcode.com/problems/sum-of-square-numbers) | |

python/merge_two_binary_trees.py

@@ -0,0 +1,16 @@
+# Definition for a binary tree node.
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+
+class Solution:
+    def mergeTrees(self, root1: TreeNode, root2: TreeNode) -> TreeNode:
+        if root1 is None: return root2
+        if root2 is None: return root1
+        root1.val += root2.val
+        root1.left = self.mergeTrees(root1.left, root2.left)
+        root1.right = self.mergeTrees(root1.right, root2.right)
+        return root1

src/MergeTwoBinaryTrees.java

@@ -0,0 +1,25 @@
+public class MergeTwoBinaryTrees {
+    public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {
+        if (root1 == null) return root2;
+        if (root2 == null) return root1;
+        root1.val += root2.val;
+        root1.left = mergeTrees(root1.left, root2.left);
+        root1.right = mergeTrees(root1.right, root2.right);
+        return root1;
+    }
+
+    private void mergeTrees(TreeNode result, TreeNode root1, TreeNode root2) {
+        if (root1 == null && root2 == null) return;
+        if (root1 == null) result.val = root2.val;
+        else if (root2 == null) result.val = root1.val;
+        else result.val = root1.val + root2.val;
+        if ((root1 != null && root1.left != null) || (root2 != null && root2.left != null)) {
+            result.left = new TreeNode();
+            mergeTrees(result.left, root1 == null ? null : root1.left, root2 == null ? null : root2.left);
+        }
+        if ((root1 != null && root1.right != null) || (root2 != null && root2.right != null)) {
+            result.right = new TreeNode();
+            mergeTrees(result.right, root1 == null ? null : root1.right, root2 == null ? null : root2.right);
+        }
+    }
+}