K 个一组翻转链表

题目：https://leetcode-cn.com/problems/reverse-nodes-in-k-group/

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func reverseKGroup(head *ListNode, k int) *ListNode {
    if k <= 1 || head == nil || head.Next == nil {
	return head
    } 
    start,end,next,oldEnd, count := head,head,head,head, 0
    for loop := 1;end != nil; loop++{
        if loop % k == 0 {
            next,end.Next = end.Next, nil
            newHead := reverseList(start)
            if loop == k {
                head = newHead
            }else{
                oldEnd.Next, oldEnd = newHead, start
            }
            start.Next,start,end = next,next,next
        }else{
            end = end.Next
            count++
        }
    }
    if count % k == 0 {
        reverseList(start)
    }
    return head
}

func reverseList(head *ListNode) *ListNode {
    var prev *ListNode
    for head != nil  {
        head.Next, prev, head = prev, head, head.Next
    }
    return prev
}

路漫漫其修远兮！