1302.层数最深叶子节点的和

1302.层数最深叶子节点的和

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algorithms	Medium (82.69%)	129	-

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给你一棵二叉树的根节点 root ，请你返回 层数最深的叶子节点的和 。

示例 1：

输入：root = [1,2,3,4,5,null,6,7,null,null,null,null,8] 输出：15
示例 2：
输入：root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5] 输出：19

提示：

• 树中节点数目在范围 [1, 104] 之间。
• 1 <= Node.val <= 100

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Discussion | Solution

思路

按题意层序遍历模拟即可

解答

/*
 * @lc app=leetcode.cn id=1302 lang=javascript
 *
 * [1302] 层数最深叶子节点的和
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var deepestLeavesSum = function (root) {
  let sum = 0;
  const queue = [root];
  while (queue.length) {
    const row = queue.splice(0, queue.length);
    const temp = [];
    let rowSum = 0;
    while (row.length) {
      const node = row.shift();
      rowSum += node.val;
      if (node.left) temp.push(node.left);
      if (node.right) temp.push(node.right);
    }
    sum = rowSum;
    queue.push(...temp);
  }
  return sum;
};
// @lc code=end