题解 | #从上往下打印二叉树#

package main

import . "nc_tools"

/*
 * type TreeNode struct {
 *   Val int
 *   Left *TreeNode
 *   Right *TreeNode
 * }
 */

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * @param root TreeNode类
 * @return int整型一维数组
 */
func PrintFromTopToBottom(root *TreeNode) []int {
	// write code here
	if root == nil {
		return nil
	}

	var queue []*TreeNode
	queue = append(queue, root)

	var ret []int
	for len(queue) > 0 {
		size := len(queue)
		for i := 0; i < size; i++ {
			cur := queue[0]
			ret = append(ret, cur.Val)

			queue = queue[1:]

			if cur.Left != nil {
				queue = append(queue, cur.Left)
			}
			if cur.Right != nil {
				queue = append(queue, cur.Right)
			}
		}
	}

	return ret
}