[LeetCode] Reorder List

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Given a singly linked list L: L₀→L₁→…→L_n-1→L_n,
reorder it to: L₀→L_n→L₁→L_n-1→L₂→L_n-2→…

You must do this in-place without altering the nodes' values.

For example,
Given {1,2,3,4}, reorder it to {1,4,2,3}

LeetCode: https://oj.leetcode.com/problems/reorder-list/

题解：本题要求对一个链表进行重新链接，可以通过将节点保存在一个堆栈和队列中的方法类操作；但Java基础类库里面提供Deque（双向链表实现），所以我们可以通过以下方式实现：

public class Solution {    public void reorderList(ListNode head) {       if(head == null || head.next == null)return ;Deque deque = new LinkedList<ListNode>();ListNode current = head;while(current != null){deque.addLast(current);current = current.next;}ListNode result = new ListNode(0);while(!deque.isEmpty()){result.next = (ListNode) deque.pollFirst();result = result.next;if(!deque.isEmpty()){result.next = (ListNode) deque.pollLast();result = result.next;}}result.next = null;    }}

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