Lstmxx的空间

637. 二叉树的层平均值

给定一个非空二叉树, 返回一个由每层节点平均值组成的数组。

/**
 * 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 averageOfLevels(root: TreeNode | null): number[] {
  const res: number[] = []
  if (root === null) return res
  const nodeQues: TreeNode[] = [root]
  while(nodeQues.length > 0) {
    const nodes = nodeQues.splice(0)
    const len = nodes.length
    let sum = 0
    for(let i = 0; i < len; i++) {
      const node = nodes[i]
      sum += node.val
      node.left && nodeQues.push(node.left)
      node.right && nodeQues.push(node.right)
    }
    res.push(sum / len)
  }
  return res
};