update: 0104.二叉树的最大深度: 优化python代码

problems/0102.二叉树的层序遍历.md

@@ -2532,20 +2532,18 @@ class Solution:
             return 0
         
         queue_ = [root]
-        result = []
+        depth = 0
         while queue_:
             length = len(queue_)
-            sub = []
             for i in range(length):
                 cur = queue_.pop(0)
                 sub.append(cur.val)
                 #子节点入队列
                 if cur.left: queue_.append(cur.left)
                 if cur.right: queue_.append(cur.right)
-            result.append(sub)
+            depth += 1
             
-
-        return len(result)
+        return depth
 ```
 
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