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);
}
}
