Lstmxx的空间

1302. 层数最深叶子节点的和

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 。

/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */

function deepestLeavesSum(root: TreeNode | null): number {
  let res = 0
  if (root === null) return res
  const nodeQue: TreeNode[] = [root]
  while(nodeQue.length) {
    const nodes = nodeQue.splice(0)
    const len = nodes.length
    for(let i = 0; i < len; i++) {
      const node = nodes[i]
      if (node.left) {
        nodeQue.push(node.left)
      }
      if (node.right) {
        nodeQue.push(node.right)
      }
    }
    if (nodeQue.length === 0) {
      res = nodes.reduce((pre, node) => {
        pre += node.val
        return pre
      }, 0)
    }
  }
  return res
};