Maximum Level Sum of a Binary Tree

Author: anantkaushik

1161-maximum-level-sum-of-a-binary-tree.py

@@ -0,0 +1,51 @@
+"""
+Problem Link: https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree/
+
+Given the root of a binary tree, the level of its root is 1, the level of its children is 2, and so on.
+Return the smallest level X such that the sum of all the values of nodes at level X is maximal.
+
+Example 1:
+Input: [1,7,0,7,-8,null,null]
+Output: 2
+Explanation: 
+Level 1 sum = 1.
+Level 2 sum = 7 + 0 = 7.
+Level 3 sum = 7 + -8 = -1.
+So we return the level with the maximum sum which is level 2.
+ 
+Note:
+The number of nodes in the given tree is between 1 and 10^4.
+-10^5 <= node.val <= 10^5
+"""
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    def maxLevelSum(self, root: TreeNode) -> int:
+        level = maxLevel = 0
+        if not root:
+            return maxLevel
+        queue = [[root]]
+        maxSum = float('-inf')
+        while queue:
+          level += 1
+          levelNodes = queue.pop(0)
+          nextLevel = []
+          levelSum = 0
+          while levelNodes:
+            node = levelNodes.pop()
+            levelSum +=node.val
+            if node.left:
+              nextLevel.append(node.left)
+            if node.right:
+              nextLevel.append(node.right)
+          if nextLevel:
+            queue.append(nextLevel)
+          if levelSum > maxSum:
+            maxSum = levelSum
+            maxLevel = level
+        return maxLevel