[剑指offer]面试题第[36]题[JAVA][二叉搜索树与双向链表][递归]

你的名字 2023-03-01 09:29 11阅读 0赞

#### 【问题描述】\[中等\] ####

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#### 【解答思路】 ####

###### 中序遍历 ######

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![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70 7]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RhZG9uZ3d1ZGk_size_16_color_FFFFFF_t_70 8]

**时间复杂度：O(N) 空间复杂度：O(N)**  
![在这里插入图片描述][20200723151556123.png]

class Solution { 
        Node pre, head;
        public Node treeToDoublyList(Node root) { 
            if(root == null) return null;
            dfs(root);
            head.left = pre;
            pre.right = head;
            return head;
        }
        void dfs(Node cur) { 
            if(cur == null) return;
            dfs(cur.left);
            if(pre != null) pre.right = cur;
            else head = cur;
            cur.left = pre;
            pre = cur;
            dfs(cur.right);
        }
    }

#### 【总结】 ####

###### 1.二叉搜索树中序遍历 ######

// 打印中序遍历
    void dfs(TreeNode root) { 
        if(root == null) return;
        dfs(root.left); // 左
        System.out.println(root.val); // 根
        dfs(root.right); // 右
    }

###### 2.二叉搜索树中序遍历 单调地震 ######

###### 3.树 递归 画图 ######

作者：Krahets  
转载链接：https://leetcode-cn.com/problems/er-cha-sou-suo-shu-yu-shuang-xiang-lian-biao-lcof/solution/mian-shi-ti-36-er-cha-sou-suo-shu-yu-shuang-xian-5/

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[20200723151556123.png]: https://img-blog.csdnimg.cn/20200723151556123.png