LeetCode 풀기 - 226. Invert Binary Tree

226. Invert Binary Tree

문제)

Given the root of a binary tree, invert the tree, and return its root.

 

솔루션1)

# 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 invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:           
        self.invert(root)
        return root
    
    def invert(self, node):
        if node is None:
            return
        
        # swap        
        node.right, node.left = node.left, node.right
        
        # go child
        self.invert(node.left)
        self.invert(node.right)

솔루션2)

# 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 invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:           
        if not root:
            return root
        
        # swap
        root.left, root.right = root.right, root.left
        
        self.invertTree(root.left)
        self.invertTree(root.right)
        
        return root