题解 | #链表内指定区间反转#

package main

// import "fmt"
import . "nc_tools"

/*
 * type ListNode struct{
 *   Val int
 *   Next *ListNode
 * }
 */

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 *
 * @param head ListNode类
 * @param m int整型
 * @param n int整型
 * @return ListNode类
 */
func reverseBetween(head *ListNode, m int, n int) *ListNode {
	// write code here

	var start, end *ListNode
    dummy := new(ListNode)
    dummy.Next = head
	start = dummy
	for i := 0; i < m-1; i++ {
		start = start.Next
	}
	end = start.Next
	for i := 0; i <= n-m; i++ {
		if end != nil {
			end = end.Next
		}
	}
	p := start.Next
	start.Next = end
	for i := 0; i <= n-m && p != nil; i++ {
		tmp := p
		p = p.Next
		tmp.Next = start.Next
		start.Next = tmp
	}
	return dummy.Next
}