public class Solution
extends Object
1161 - Maximum Level Sum of a Binary Tree\.
Medium
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