[Day16]-[链表] 反转链表

输入：head = [1,2,3,4,5]输出：[5,4,3,2,1]

输入：head = [1,2]输出：[2,1]

输入：head = []输出：[]

/** * Definition for singly-linked list. * type ListNode struct { *     Val int *     Next *ListNode * } */func reverseList(head *ListNode) *ListNode {	var solution func(head *ListNode) *ListNode	solution = func(head *ListNode) *ListNode {		var new *ListNode		current := head		for current != nil {			next := current.Next			current.Next, new = new, current			current = next		}		return new	}    return solution(head)}

func TestReverseList(t *testing.T) {	var solution func(head *ListNode) *ListNode	solution = func(head *ListNode) *ListNode {		new := &ListNode{} // 重新初始化新链表		for head != nil {			current := &ListNode{ // 新增一个节点				Val:  head.Val,				Next: nil,			}			// 0->1->2			// 0->2 => 1->0			current.Next = new.Next			new.Next = current			head = head.Next		}		return new.Next	}	t.Log(solution(GetListNode()))}