142-206. 反转链表

反转一个单链表。(第一个我写的,其他的你猜)
class Solution(object):
    def reverseList1(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        new_head = ListNode(-1)
        temp = head  # 记录当前节点
        pre = None   # 记录当前节点的上一个节点
        while temp:
            new_head.next = temp  # 将新节点的next执行temp
            cur = temp  # 记录当前节点
            temp = temp.next  # 记录下一个节点
            cur.next = pre  # 改变当前节点的下一个节点
            pre = cur  # 更新temp的上一个节点
        return new_head.next

    def search(self, root):
        """遍历"""
        temp = root
        print(temp.val)
        while temp.next:
            temp = temp.next
            print(temp.val)

    def reverseList2(self, head):
        """我一直梦想达到这个水平但是却离得更远
        :type head: ListNode
        :rtype: ListNode
        """
        cur, pre = head, None
        while cur:
            pre ,cur.next, cur = cur, pre, cur.next
        return pre

    def reverseList(self, head):
        """类似于reverseList2,但是人家的更灵巧
        :type head: ListNode
        :rtype: ListNode
        """
        pre = None
        cur = head
        while cur:
            tmp = cur.next
            cur.next = pre

            pre = cur
            cur = tmp
        return pre


if __name__ == '__main__':
    root = ListNode(1)
    n2 = ListNode(2)
    n3 = ListNode(3)
    n4 = ListNode(4)
    n5 = ListNode(5)

    n4.next = n5
    n3.next = n4
    n2.next = n3

    root.next = n2

    s = Solution()
    new_node = s.reverseList(root)
    s.search(new_node)