1302. Deepest Leaves Sum

Question

Given the root of a binary tree, return the sum of values of its deepest leaves.

Solution

BFS搜索，层序遍历，每次计算每个层级的总和。
最后返回最后一个层级总和。

Code

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public int deepestLeavesSum(TreeNode root) {
        Deque<TreeNode> q = new LinkedList<>();
        int res = 0;
        
        q.offer(root);
        
        int level = q.size();
        
        while(!q.isEmpty()){
            int sum = 0;
            for(int i = 0; i < level; i++){
                TreeNode curr = q.poll();
                sum += curr.val;
                if(curr.left != null) q.offer(curr.left);
                if(curr.right != null) q.offer(curr.right);
            }
            res = sum;
            level = q.size();
        }
        return res;
    }
}