迭代 递归 反转链表 反转二叉树

https://leetcode-cn.com/problems/reverse-linked-list/

反转链表  迭代 递归

https://leetcode-cn.com/problems/invert-binary-tree/

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/**  * Definition for a binary tree node.  * type TreeNode struct {  *     Val int  *     Left *TreeNode  *     Right *TreeNode  * }  */ func swap(root *TreeNode) {     if root != nil {         t := root.Left         root.Left = root.Right         root.Right = t     } } func invertTree(root *TreeNode) *TreeNode {     if root != nil {         swap(root)         invertTree(root.Left)         invertTree(root.Right)     }     return root }

　　https://leetcode-cn.com/problems/invert-binary-tree/solution/fan-zhuan-er-cha-shu-by-leetcode-solution/

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func invertTree(root *TreeNode) *TreeNode {     if root == nil {         return nil     }     left := invertTree(root.Left)     right := invertTree(root.Right)     root.Left = right     root.Right = left     return root }

　　

https://leetcode.cn/problems/swap-nodes-in-pairs/solution/liang-liang-jiao-huan-lian-biao-zhong-de-jie-di-91/