二刷hot100-114.二叉树展开为链表

将二叉树按照先序遍历的顺序展开为链表先序遍历中左右这里用一种思想先处理右节点然后记录处理好的右链表头总之是右左中的处理顺序/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode() {} * TreeNode(int val) { this.val val; } * TreeNode(int val, TreeNode left, TreeNode right) { * this.val val; * this.left left; * this.right right; * } * } */ class Solution { TreeNode node; public void flatten(TreeNode root) { if(root null){ return; } flatten(root.right); flatten(root.left); root.left null; root.right node; node root; } }