LeetCode 897. 递增顺序查找树

题目链接

897. 递增顺序查找树 easy

题目思路

这个题有点像二叉树变单链表，利用中序遍历去进行更改即可。

代码实现

class Solution {
    TreeNode head;
    TreeNode pre;
    public TreeNode increasingBST(TreeNode root) {
        helper(root);
        return head;
    }
    public void helper(TreeNode root){
        if(root == null){
            return;
        }
        helper(root.left);
        if(head == null){
            head = root;
        }else{
            pre.left = null;
            pre.right = root;
        }
        pre = root;
        helper(root.right);
    }
}