feat:

Author: junbinding

tree.symmetric-tree.py

@@ -0,0 +1,30 @@
+# Definition for a binary tree node.
+class TreeNode:
+    def __init__(self, x):
+        self.val = x
+        self.left = None
+        self.right = None
+
+class Solution:
+    """
+    101. 对称二叉树
+    https://leetcode-cn.com/problems/symmetric-tree/
+    给定一个二叉树，检查它是否是镜像对称的。
+    """
+    def isSymmetric(self, root: TreeNode) -> bool:
+        if not root:
+            return True
+
+        def dfs(left, right):
+            if not left or not right:
+                return True
+
+            if not (left and right):
+                return False
+
+            if left.val != right.val:
+                return False
+
+            return dfs(left.left, right.right) and dfs(left.right, right.left)
+
+        return dfs(root.left, root.right)