LeetCode: 637 solved

Author: devMEremenko

Python/LeetCode/637. Average of Levels in Binary Tree.py

@@ -0,0 +1,45 @@
+# https://leetcode.com/problems/average-of-levels-in-binary-tree/
+
+from collections import deque
+
+# Definition for a binary tree node.
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+class Solution:
+    def averageOfLevels(self, root: TreeNode) -> [float]:
+        if not root: 
+            return []
+        
+        empty_node = TreeNode(val=None)
+        
+        q = deque([root, empty_node])
+        lvl_total = 0
+        lvl_items_count = 0
+        res = []
+        
+        while q:
+            node = q.popleft()
+            
+            if node.val is None:                    
+                res.append(lvl_total / lvl_items_count)
+                lvl_total = 0
+                lvl_items_count = 0
+                
+                if not q:
+                    break
+                else:
+                    q.append(empty_node)
+            else:
+                lvl_total += node.val
+                lvl_items_count += 1
+
+                if node.left:
+                    q.append(node.left)
+                if node.right:
+                    q.append(node.right)
+                
+        return res