From 6efc66e17597da3038966c690bb75dd4f0e61ad0 Mon Sep 17 00:00:00 2001
From: Baturu <45113401+z80160280@users.noreply.github.com>
Date: Sat, 5 Jun 2021 18:13:20 -0700
Subject: [PATCH] =?UTF-8?q?Update=200110.=E5=B9=B3=E8=A1=A1=E4=BA=8C?=
 =?UTF-8?q?=E5=8F=89=E6=A0=91.md?=
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---
 problems/0110.平衡二叉树.md | 56 ++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/problems/0110.平衡二叉树.md b/problems/0110.平衡二叉树.md
index 1cd54849..b9d01503 100644
--- a/problems/0110.平衡二叉树.md
+++ b/problems/0110.平衡二叉树.md
@@ -498,6 +498,62 @@ class Solution {
 
 Python：
 
+> 递归法：
+```python
+class Solution:
+    def isBalanced(self, root: TreeNode) -> bool:
+        return True if self.getDepth(root) != -1 else False
+    
+    #返回以该节点为根节点的二叉树的高度，如果不是二叉搜索树了则返回-1
+    def getDepth(self, node):
+        if not node:
+            return 0
+        leftDepth = self.getDepth(node.left)
+        if leftDepth == -1: return -1 #说明左子树已经不是二叉平衡树
+        rightDepth = self.getDepth(node.right)
+        if rightDepth == -1: return -1 #说明右子树已经不是二叉平衡树
+        return -1 if abs(leftDepth - rightDepth)>1 else 1 + max(leftDepth, rightDepth)
+```
+
+> 迭代法：
+```python
+class Solution:
+    def isBalanced(self, root: TreeNode) -> bool:
+        st = []
+        if not root:
+            return True
+        st.append(root)
+        while st:
+            node = st.pop() #中
+            if abs(self.getDepth(node.left) - self.getDepth(node.right)) > 1:
+                return False
+            if node.right:
+                st.append(node.right) #右（空节点不入栈）
+            if node.left:
+                st.append(node.left) #左（空节点不入栈）
+        return True
+    
+    def getDepth(self, cur):
+        st = []
+        if cur:
+            st.append(cur)
+        depth = 0
+        result = 0
+        while st:
+            node = st.pop()
+            if node:
+                st.append(node) #中
+                st.append(None)
+                depth += 1
+                if node.right: st.append(node.right) #右
+                if node.left: st.append(node.left) #左
+            else:
+                node = st.pop()
+                depth -= 1
+            result = max(result, depth)
+        return result
+```
+
 
 Go：
 ```Go