算法—leetcode—226

题目

226. 翻转二叉树

题目描述

翻转一棵二叉树。

思路

1.前序遍历二叉树
2.定义一个临时变量用于存储临时二叉树节点
3.左右子数进行交换

示例

data := &TreeNode{
	Val:4,
	Left:&TreeNode{
		Val:2,
		Left:&TreeNode{Val:1},
		Right:&TreeNode{Val:3},
	},
	Right:&TreeNode{
		Val:7,
		Left:&TreeNode{Val:7},
		Right:&TreeNode{Val:9},
	},
}

返回
{"Val":4,"Left":{"Val":7,"Left":{"Val":9,"Left":null,"Right":null},"Right":{"Val":7,"Left":null,"Right":null}},"Right":{"Val":2,"Left":{"Val":3,"Left":null,"Right":null},"Right":{"Val":1,"Left":null,"Right":null}}}

代码

package leetcode

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

// invertTree
// 翻转二叉树
func invertTree(root *TreeNode) *TreeNode {
    var node *TreeNode
    
    var preOrder func(root *TreeNode)
    preOrder = func(root *TreeNode){
        if root == nil{
            return
        }
        node = root.Left
        root.Left = root.Right
        root.Right = node
        
        preOrder(root.Left)
        preOrder(root.Right)
    }
    preOrder(root)
    return root
}

参考

来源：力扣（LeetCode）
链接：leetcode-cn.com/problems/in…
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