Create 101. Symmetric Tree.py

Author: xulzee

101. Symmetric Tree.py

@@ -0,0 +1,44 @@
+# -*- coding: utf-8 -*-
+# @Time    : 2019/3/6 14:35
+# @Author  : xulzee
+# @Email   : [email protected]
+# @File    : 101. Symmetric Tree.py
+# @Software: PyCharm
+
+# Definition for a binary tree node.
+class TreeNode:
+    def __init__(self, x):
+        self.val = x
+        self.left = None
+        self.right = None
+
+
+class Solution:
+    def isSymmetricHelper(self, left: TreeNode, right: TreeNode) -> bool:
+        if left is None and right is None:
+            return True
+        if (left is None and right != None) or (left != None and right == None) or (left.val != right.val):
+            return False
+        return self.isSymmetricHelper(left.left, right.right) and self.isSymmetricHelper(left.right, right.left)
+
+    def isSymmetric1(self, root: TreeNode) -> bool:
+        if root == None:
+            return True
+        return self.isSymmetricHelper(root.left, root.right)
+
+    def isSymmetric(self, root: TreeNode) -> bool:
+        q = []
+        q.append(root)
+        q.append(root)
+        while len(q) != 0:
+            left = q.pop(0)
+            right = q.pop(0)
+            if left is None and right is None:
+                continue
+            if (left is None and right is not None) or (left is not None and right is None) or (left.val != right.val):
+                return False
+            q.append(left.left)
+            q.append(right.right)
+            q.append(left.right)
+            q.append(right.left)
+        return True