Merge pull request #1200 from Camille0512/master

Add one more python code

problems/0098.验证二叉搜索树.md

@@ -408,7 +408,28 @@ class Solution:
         return True
 
 ```
-## Go 
+```python
+# 遵循Carl的写法，只添加了节点判断的部分
+class Solution:
+    def isValidBST(self, root: TreeNode) -> bool:
+        # method 2
+        que, pre = [], None
+        while root or que:
+            while root:
+                que.append(root)
+                root = root.left
+            root = que.pop()
+            # 对第一个节点只做记录，对后面的节点进行比较
+            if pre is None:
+                pre = root.val
+            else:
+                if pre >= root.val: return False
+                pre = root.val
+            root = root.right
+        return True
+```
+
+## Go
 
 ```Go
 import "math"

problems/0101.对称二叉树.md

@@ -437,41 +437,6 @@ class Solution:
         return True
 ```
 
-层序遍历
-
-```python
-class Solution:
-    def isSymmetric(self, root: TreeNode) -> bool:
-        if not root: return True
-        que, cnt = [[root.left, root.right]], 1
-        while que:
-            nodes, tmp, sign = que.pop(), [], False
-            for node in nodes:
-                if not node:
-                    tmp.append(None)
-                    tmp.append(None)
-                else:
-                    if node.left:
-                        tmp.append(node.left)
-                        sign = True
-                    else:
-                        tmp.append(None)
-                    if node.right:
-                        tmp.append(node.right)
-                        sign = True
-                    else:
-                        tmp.append(None)
-            p1, p2 = 0, len(nodes) - 1
-            while p1 < p2:
-                if (not nodes[p1] and nodes[p2]) or (nodes[p1] and not nodes[p2]): return False
-                elif nodes[p1] and nodes[p2] and nodes[p1].val != nodes[p2].val: return False
-                p1 += 1
-                p2 -= 1
-            if sign: que.append(tmp)
-            cnt += 1
-        return True
-```
-
 ## Go
 
 ```go