题解 | #求二叉树的层序遍历#

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整型二维数组
 */


func levelOrder(root *TreeNode) [][]int {

	list := make([][]int, 0)
	Level(root, &list, 1)
	return list
}

// append扩容导致导致生成新数组
func Level(root *TreeNode, list *[][]int, depth int) {
	if root == nil {
		return
	}
	
    if len(*list) < depth {
        *list = append(*list, []int{root.Val})
    } else {
        (*list)[depth-1] = append((*list)[depth-1], root.Val)
    }
	depth++
	Level(root.Left, list, depth)
	Level(root.Right, list, depth)
	
}