<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.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int maxLevelSum(TreeNode* root) {
        stack<TreeNode*> q1, q2;
        bool parity = false;
        q2.push(root);
        int max_count = root->val; int count = 0; int level = 1;
        int temp_level = 1;
        while (!q1.empty() || !q2.empty()) {
            if (temp_level % 2 == 0) {
                TreeNode* node = q1.top();
                q1.pop();
                if (node->left) q2.push(node->left);
                if (node->right) q2.push(node->right);
                count += node->val;
                // cout << count << " " << max_count << endl;
                if (q1.empty()) {
                    // cout << count << " " << max_count << endl;
                    if (count > max_count) {
                        max_count = count;
                        level = temp_level;
                    }
                    count = 0;
                    temp_level++;
                }
            } else {
                TreeNode* node = q2.top();
                q2.pop();
                if (node->left) q1.push(node->left);
                if (node->right) q1.push(node->right);
                // if (temp_level == 3)
                // cout << node->val << " " << count << " " << max_count << endl;
                count += node->val;
                if (q2.empty()) {
                    // cout << count << " " << max_count << endl;
                    if (count > max_count) {
                        max_count = count;
                        level = temp_level;
                    }
                    count = 0;
                    temp_level++;
                }
            }
        }
        return level;
    }
};
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