1161.Maximum Level Sum of a Binary Tree.cpp

/**
 * 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)
    {
        if (!root)
            return 0;

        int maxSum = root->val;
        int maxLevel = 1;
        int level = 1;

        queue<TreeNode *> q;
        q.push(root);

        while (!q.empty())
        {
            int size = q.size();
            int currentSum = 0;

            for (int i = 0; i < size; i++)
            {
                TreeNode *node = q.front();
                q.pop();

                currentSum += node->val;

                if (node->left)
                    q.push(node->left);

                if (node->right)
                    q.push(node->right);
            }

            if (currentSum > maxSum)
            {
                maxSum = currentSum;
                maxLevel = level;
            }

            level++;
        }

        return maxLevel;
    }
};