题解 | #从上往下打印二叉树# | Golang

package main

/*
 * 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 {
    ans := []int{}
    q := []*TreeNode{}
    if root != nil {
        q = append(q, root)
    }
    for len(q) != 0 {
        n := len(q)
        for ; n >= 1; n-- {
            front := q[0]
            ans = append(ans, front.Val)
            if front.Left != nil {
                q = append(q, front.Left)
            }
            if front.Right != nil {
                q = append(q, front.Right)
            }
            q = q[1:]
        }
    }
    return ans
}