1161. Maximum Level Sum of a Binary Tree

https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree

Description

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:** root = [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.

Example 2:

**Input:** root = [989,null,10250,98693,-89388,null,null,null,-32127]
**Output:** 2

Constraints:

• The number of nodes in the tree is in the range [1, 104].

• -105 <= Node.val <= 105

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