[LeetCode] Reverse Linked List II

转载于 2015-09-01 23:55:00 发布 · 48 阅读

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原文链接：http://www.cnblogs.com/jcliBlogger/p/4777400.html

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#开发工具

本文介绍了一种在链表中实现链表反转的方法，通过创建一个新的头节点并使用该节点来定位并操作链表中的节点，实现了从第m个节点到第n个节点之间的链表反转。具体步骤包括初始化新头节点、遍历链表至指定位置、重新连接链表节点等。

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The basic idea is as follows:

Create a new_head that points to head and use it to locate the immediate node before them-th (notice that it is 1-indexed) node pre;
Set cur to be the immediate node after pre and at each time move the immediate node after cur (named move) to be the immediate node after pre. Repeat it for n - m times.

 1 class Solution {  
 2 public:
 3     ListNode* reverseBetween(ListNode* head, int m, int n) {
 4         ListNode* new_head = new ListNode(0);
 5         new_head -> next = head;
 6         ListNode* pre = new_head;
 7         for (int i = 0; i < m - 1; i++)
 8             pre = pre -> next;
 9         ListNode* cur = pre -> next;
10         for (int i = 0; i < n - m; i++) {
11             ListNode* move = cur -> next; 
12             cur -> next = move -> next;
13             move -> next = pre -> next;
14             pre -> next = move;
15         }
16         return new_head -> next;
17     }
18 };