【hot100-java】二叉树展开为链表

二叉树篇。

/*** 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 {//1.将传入的树转为右斜线树public void flatten(TreeNode root) {//2.极小if(root==null){return;}if(root.left==null&&root.right==null){return;}//3.极大//3.1if(root.left==null){flatten(root.right);return;}//3.2else{//3.2.1 变为线型flatten(root.left);flatten(root.right);//3.2.2 右子树拼到左子树右下角TreeNode temp=root.left;while(temp.right!=null){temp=temp.right;}temp.right=root.right;//3.2.3 左子树移到右边变为root右子树root.right=root.left;//3.2.4 root左子树变为nullroot.left=null;return;}}
}

过关斩将，easy！