leetcode 206. 反轉鏈表 go 語言實現

遞歸實現與非遞歸實現，以及頭插法

/**
 * @Description: 反轉鏈表  非遞歸方式
 *
 * @Date:
 * @Author: fuGuoWen
 * @Return
 * @Throws
 */
func reverseList(head *ListNode) *ListNode {
	var pre *ListNode
	var next *ListNode
	for head != nil {
		next = head.Next
		head.Next = pre
		pre = head
		head = next
	}
	return pre
}

/**
 * @Description: 反轉鏈表  遞歸方式
 *
 * @Date:
 * @Author: fuGuoWen
 * @Return
 * @Throws
 */
func reverseList2(head *ListNode) *ListNode {

	if head == nil || head.Next == nil {
		return head
	}
	next := head.Next
	pre := reverseList2(next)
	next.Next = head
	head.Next = nil
	return pre
}

/**
 * @Description: 頭插法反轉鏈表
 * 
 * @Date:  
 * @Author: fuGuoWen
 * @Return 
 * @Throws 
 */
func reverseList3(head *ListNode) *ListNode {
	temp := ListNode{0, nil}
	temp.Next = head
	pre := temp
	q := temp.Next
	for head != nil {
		remove := q.Next
		q.Next = q.Next.Next
		remove.Next = pre.Next
		pre.Next = remove
		head = head.Next
	}

	return temp.Next
}