<p>Given the <code>root</code> of a binary tree, the level of its root is <code>1</code>, the level of its children is <code>2</code>, and so on.</p>

<p>Return the <strong>smallest</strong> level <code>x</code> such that the sum of all the values of nodes at level <code>x</code> is <strong>maximal</strong>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/05/03/capture.JPG" style="width: 200px; height: 175px;" />
<pre>
<strong>Input:</strong> root = [1,7,0,7,-8,null,null]
<strong>Output:</strong> 2
<strong>Explanation: </strong>
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.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> root = [989,null,10250,98693,-89388,null,null,null,-32127]
<strong>Output:</strong> 2
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
</ul>

# 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 dfs(self, level, current):
        if current:
            self.max_level = max(level, self.max_level)
            
            if not level in self.counts:
                self.counts[level] = 0
            
            self.counts[level] += current.val
            
            self.dfs(level + 1, current.left)
            self.dfs(level + 1, current.right)

    def maxLevelSum(self, root: Optional[TreeNode]) -> int:
        self.counts = {}
        self.max_level = 1

        self.dfs(1, root)

        max_count = self.counts[1]
        best_level = 1

        for i in range(1, self.max_level + 1):
            print(self.counts[i])

        for i in range(2, self.max_level + 1):
            if max_count < self.counts[i]:
                max_count = self.counts[i]
                best_level = i
        
        return best_level
        
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