两种解法搞定 Swap Nodes in Pairs 算法题

24. Swap Nodes in PairsSolvedMediumTopicsCompaniesGiven a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes (i.e., only nodes themselves may be changed.) 
Example 1:

Input: head = [1,2,3,4]Output: [2,1,4,3]Example 2:
Input: head = []Output: []Example 3:
Input: head = [1]Output: [1] 
Constraints:
The number of nodes in the list is in the range [0, 100].0 <= Node.val <= 100

/** * Definition for singly-linked list. * type ListNode struct { *     Val int *     Next *ListNode * } */func swapPairs(head *ListNode) *ListNode {		if head == nil || head.Next == nil {		return head	}		if head.Next.Next == nil {		next := head.Next		head.Next = nil		next.Next = head        head = next
		return head	}
	prev, cur, nxt := head, head.Next, head.Next.Next    cur.Next = prev    head = cur	prev.Next = swapPairs(nxt)
    return head}

/** * Definition for singly-linked list. * type ListNode struct { *     Val int *     Next *ListNode * } */func swapPairs(head *ListNode) *ListNode {		dump := &ListNode{Val: 0}	dump.Next = head	prevNode := dump	currentNode := head
    for currentNode != nil && currentNode.Next != nil {		prevNode.Next = currentNode.Next		currentNode.Next = currentNode.Next.Next		prevNode.Next.Next = currentNode		prevNode = currentNode		currentNode = currentNode.Next	}
	return dump.Next}