題目描述

輸入一棵二叉搜尋樹，將該二叉搜尋樹轉換成一個排序的雙向連結串列。要求不能建立任何新的結點，只能調整樹中結點指標的指向。

程式碼實現

class Solution {
public:
    TreeNode* Convert(TreeNode* pRootOfTree)
    {
        if(pRootOfTree == nullptr) return nullptr;
        TreeNode* pre = nullptr;

        convertHelper(pRootOfTree, pre);

        TreeNode* res = pRootOfTree;
        while
 
(res ->left)
            res = res ->left;
        return res;
    }

    void convertHelper(TreeNode* cur, TreeNode*& pre)
    {
        if(cur == nullptr) return;

        convertHelper(cur ->left, pre);

        cur ->left = pre;
        if(pre) pre ->right = cur;
        pre = cur;

        convertHelper(cur ->
 
right, pre);



    }
};