Reverse Linked List

Reverse a singly linked list.

URL: https://leetcode.com/problems/reverse-linked-list/

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def reverseList(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        if head == None:
            return None
        elif head != None and head.next == None:
            return head
        else:
            temp = None
            next_node = None
            while head != None:
                next_node = head.next
                head.next = temp
                temp = head
                head = next_node

            return temp