[Leetcode]617. Merge Two Binary Trees

limelimejiwon·2022년 3월 15일

📄 Description

You are given two binary trees root1 and root2.

Imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not. You need to merge the two trees into a new binary tree. The merge rule is that if two nodes overlap, then sum node values up as the new value of the merged node. Otherwise, the NOT null node will be used as the node of the new tree.

Return the merged tree.

Note: The merging process must start from the root nodes of both trees.

Example 1:

Input: root1 = [1,3,2,5], root2 = [2,1,3,null,4,null,7]
Output: [3,4,5,5,4,null,7]

Example 2:

Input: root1 = [1], root2 = [1,2]
Output: [2,2]

🔨 My Solution

💻 My Submission

class Solution:
    def mergeTrees(self, root1: Optional[TreeNode], root2: Optional[TreeNode]) -> Optional[TreeNode]:
        def dfs(ptr1,ptr2):
            if ptr1.left and ptr2.left: dfs(ptr1.left,ptr2.left)
            elif ptr2.left:
            if ptr1.right and ptr2.right: dfs(ptr1.right,ptr2.right)
            elif ptr2.right:
        if start1 and start2:
        elif start1:
            return start1
            return start2
        return root1

💊 Let's make my code clean

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