Talk is cheap.

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func reverseList(head *ListNode) *ListNode {
   var pre *ListNode
   for head != nil {
       pre, head.Next, head = head, pre, head.Next
   }
   return pre
}
# 递归法
func reverseList(head *ListNode) *ListNode {
   var newHead *ListNode
   if head == nil || head.Next == nil {
       return head
   } else {
       newHead = reverseList(head.Next)
       head.Next.Next = head
       head.Next = nil
   }
   return newHead
}

func reverseList(head *ListNode) *ListNode {
   if head == nil || head.Next == nil {
       return head
   }
   dummy := &ListNode{Next: head}
   for head.Next != nil {
       cur := head.Next
       head.Next = cur.Next
       cur.Next = dummy.Next
       dummy.Next = cur
   }
   return dummy.Next
}