leetcode二叉树系列参数构造

本次以二叉树层次遍历为例：

package main

import (
	"container/list"
	"fmt"
)

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

func levelOrder(root *TreeNode) [][]int {
	result := [][]int{}
	if root == nil {
		return result
	}

	queue := list.New()
	queue.PushBack(root)

	for queue.Len() > 0 {
		levelSize := queue.Len()
		levelValues := []int{}

		for i := 0; i < levelSize; i++ {
			node := queue.Remove(queue.Front()).(*TreeNode)
			levelValues = append(levelValues, node.Val)

			if node.Left != nil {
				queue.PushBack(node.Left)
			}
			if node.Right != nil {
				queue.PushBack(node.Right)
			}
		}

		result = append(result, levelValues)
	}

	return result
}

func main() {
	// 创建一个示例二叉树
	root := &TreeNode{Val: 3}
	root.Left = &TreeNode{Val: 9}
	root.Right = &TreeNode{Val: 20}
	root.Right.Left = &TreeNode{Val: 15}
	root.Right.Right = &TreeNode{Val: 7}

	// 执行层次遍历
	result := levelOrder(root)

	// 输出结果
	fmt.Println(result)
}