invert-binary-tree solution (py)

Author: hi-rachel

invert-binary-tree/hi-rachel.py

@@ -0,0 +1,37 @@
+from typing import Optional
+
+# 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
+
+"""
+재귀 풀이
+
+TC: O(n), SC: O(n)
+n = 트리 내의 노드 수
+"""
+class Solution:
+    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
+        if not root:
+            return
+        root.left, root.right = self.invertTree(root.right), self.invertTree(root.left)
+        return root
+    
+"""
+스택 풀이
+
+TC: O(n), SC: O(n)
+"""
+class Solution:
+    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
+        stack = [root]
+        while stack:
+            node = stack.pop()
+            if not node:
+                continue
+            node.left, node.right = node.right, node.left
+            stack += [node.left, node.right]
+        return root