🌕🌗 剑指 Offer 36. 二叉搜索树与双向链表

难度: 🌕🌗

问题描述

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解法

/*
// Definition for a Node.
class Node {
    public int val;
    public Node left;
    public Node right;

    public Node() {}

    public Node(int _val) {
        val = _val;
    }

    public Node(int _val,Node _left,Node _right) {
        val = _val;
        left = _left;
        right = _right;
    }
};
*/
class Solution {
    Node head;
    Node pre;
    public Node treeToDoublyList(Node root) {
        // 思路：
        // 保存上一节点
        if(root == null) {
            return root;
        }
        mySol(root);
        pre.right = head;
        head.left = pre;
        return head;
    }

    private void mySol(Node cur) {
        // 递归终止条件
        if(cur == null) {
            return;
        }
        mySol(cur.left);
        // 单层递归逻辑
        if(pre == null) {
            head = cur;
            pre = cur;
        } else {
            pre.right = cur;
            cur.left = pre;
            pre = cur;
        }
        mySol(cur.right);
    }
}

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输出