1302. Deepest Leaves Sum.md

1302. Deepest Leaves Sum

https://leetcode.com/problems/deepest-leaves-sum/

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

Example 1:

Input: root = [1,2,3,4,5,null,6,7,null,null,null,null,8]
Output: 15

Example 2:

Input: root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5]
Output: 19

Constraints:

• The number of nodes in the tree is in the range [1, 104].
• 1 <= Node.val <= 100

代码

BFS

/**
 * 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 {
    // bfs
    public int deepestLeavesSum(TreeNode root) {
        int res = 0;
        Deque<TreeNode> queue = new ArrayDeque<>();
        queue.add(root);
        while (!queue.isEmpty()) {
            int size = queue.size();
            int cur = 0;
            for (int i = 0; i < size; i++) {
                TreeNode node = queue.poll();
                cur += node.val;
                if (node.left != null) queue.add(node.left);
                if (node.right != null) queue.add(node.right);
            }
            res = cur;
        }
        return res;
    }
}