Reverse Nodes in k-Group

sjphiChina

于 2016-07-07 12:48:40 发布

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分类专栏：刷遍数

本文链接：https://blog.youkuaiyun.com/sjphiChina/article/details/51850343

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本文介绍了一种链表操作算法——K组翻转。该算法通过递进地翻转链表中的每K个节点来改变链表的顺序。文章详细展示了如何实现这一功能，并提供了一个具体的Java代码示例。

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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode reverseKGroup(ListNode head, int k) {
        if (head == null || k <= 1) {
            return head;
        }
        ListNode dummy = new ListNode(0);
        ListNode prev = dummy;
        ListNode node = head;
        dummy.next = head;
        int count = 0;
        while (node != null) {
            count++;
            ListNode next = node.next;
            if (count == k) {
                prev = helper(prev, next);
                count = 0;
            }
            node = next;
        }
        return dummy.next;
    }
    
    private ListNode helper(ListNode prev, ListNode next){
        ListNode last = prev.next;
        ListNode cur = last.next;
        while (cur != next) {
            last.next = cur.next;
            cur.next = prev.next;
            prev.next = cur;
            cur = last.next;
        }
        return last;
    }
}