1302_Deepest_Leaves_Sum.java

/*
 * 1302. Deepest Leaves Sum
 * Problem Link: https://leetcode.com/problems/deepest-leaves-sum/
 * Difficulty:   Medium
 * 
 * Solution Created by: Muhammad Khuzaima Umair
 * LeetCode : https://leetcode.com/mkhuzaima/
 * Github   : https://github.com/mkhuzaima
 * LinkedIn : https://www.linkedin.com/in/mkhuzaima/
 */

class Solution {
    public int deepestLeavesSum(TreeNode root) {
        Queue<TreeNode> q = new LinkedList<>();

        q.add(root);

        int sum = 0;
        while (!q.isEmpty()) {
            sum = 0;

            // for all nodes at this level
            for (int count = q.size(); count > 0; count--) {
                TreeNode n = q.poll();
                sum += n.val;

                // add children to queue (for next level)
                if (n.left != null) q.add(n.left);
                if (n.right != null) q.add(n.right);
            }
        }
        return sum;
    }
}