1302. 层数最深叶子节点的和

给你一棵二叉树，请你返回层数最深的叶子节点的和。

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    //bfs
    private int bfs(TreeNode root){
        if(root == null) return 0;
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        int sum=0;
        while(!queue.isEmpty()){
            sum = 0;
            int size = queue.size();
            for(int i = 0; i < size; i++){
                TreeNode q = queue.poll();
                sum += q.val;
                if(q.left != null) queue.offer(q.left);
                if(q.right != null) queue.offer(q.right);
            }
            
        }
        return sum; 
    }

    public int deepestLeavesSum(TreeNode root) {
        return bfs(root);
    }
}