From fde18e8fddd5e2686ab46157344b5b3bbdb3d715 Mon Sep 17 00:00:00 2001
From: Wen Liang <wenslife@outlook.com>
Date: Fri, 3 Sep 2021 08:36:36 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BC=98=E5=8C=96=200102.=E4=BA=8C=E5=8F=89?=
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---
 problems/0102.二叉树的层序遍历.md | 41 ++++++++++++++-----------------
 1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/problems/0102.二叉树的层序遍历.md b/problems/0102.二叉树的层序遍历.md
index 07708e5a..4a0f62e0 100644
--- a/problems/0102.二叉树的层序遍历.md
+++ b/problems/0102.二叉树的层序遍历.md
@@ -633,32 +633,29 @@ python代码：
 
 ```python
 class Solution:
+    """二叉树层平均值迭代解法"""
+
     def averageOfLevels(self, root: TreeNode) -> List[float]:
+        results = []
         if not root:
-            return []
+            return results
         
-        quene = deque([root])
-        out_list = []
-
-        while quene:
-            in_list = []
-
-            for _ in range(len(quene)):
-                node = quene.popleft()
-                in_list.append(node.val)
-                if node.left:
-                    quene.append(node.left)
-                if node.right:
-                    quene.append(node.right)
-
-            out_list.append(in_list)
-
-        out_list = map(lambda x: sum(x) / len(x), out_list)
-    
-        return out_list
+        from collections import deque
+        que = deque([root])
         
-# 执行用时：56 ms, 在所有 Python3 提交中击败了81.48%的用户
-# 内存消耗：17 MB, 在所有 Python3 提交中击败了89.68%的用户
+        while que:
+            size = len(que)
+            sum_ = 0
+            for _ in range(size):
+                cur = que.popleft()
+                sum_ += cur.val
+                if cur.left:
+                    que.append(cur.left)
+                if cur.right:
+                    que.append(cur.right)
+            results.append(sum_ / size)
+
+        return results
 ```
 
 java: