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  • bstToDoublyList

    bstToDoublyList

    bstToDoublyList

    Table of Contents

    1 描述

    将一个二叉查找树按照中序遍历转换成双向链表。

    2 样例

    给定一个二叉查找树:

        4
       / 
      2   5
     / 
    1   3
    

    返回 1<->2<->3<->4<->5

    3 解决方案

    做一个中序递归,用head保存首节点,用tail不断更新之后的每个节点。

    /**
     * Definition of TreeNode:
     * public class TreeNode {
     *     public int val;
     *     public TreeNode left, right;
     *     public TreeNode(int val) {
     *         this.val = val;
     *         this.left = this.right = null;
     *     }
     * }
     * Definition for Doubly-ListNode.
     * public class DoublyListNode {
     *     int val;
     *     DoublyListNode next, prev;
     *     DoublyListNode(int val) {
     *         this.val = val;
     *         this.next = this.prev = null;
     *     }
     * }
     */
    public class Solution {
        private DoublyListNode head = null;
        private DoublyListNode tail = null;
        /**
         * @param root: The root of tree
         * @return: the head of doubly list node
         */
        public DoublyListNode bstToDoublyList(TreeNode root) {
            // Write your code here
            if (null == root) {
                return null;
            }
            bstToDoublyList(root.left);
    
            DoublyListNode node = new DoublyListNode(root.val);
            if (null == head) {
                head = node;
                tail = node;
            } else {
                tail.next = node;
                node.prev = tail;
                tail = node;
            }
    
            bstToDoublyList(root.right);
    
            return head;
        }
    }
    

    Date: 2017-06-26 21:57

    Author: WEN YANG

    Created: 2017-06-26 Mon 22:03

    Emacs 25.2.1 (Org mode 8.2.10)

    Validate

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  • 原文地址:https://www.cnblogs.com/yangwen0228/p/7082711.html
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