reverse_linked_list.py

# Write a function that takes in the head of a Singly Linked List
# (assume that the list has at least 1 node; in other words, the head will never be a null value).
# The function should reverse the list and return its new head. Note that every node in the Singly Linked List
# has a "value" property storing its value as well as a "next" property pointing to the next node in the list
# or None (null) if it is the tail of the list.


def reverseLinkedList(head):
    p1, p2 = None, head
    while p2:
        p3 = p2.next
        p2.next = p1
        p1 = p2
        p2 = p3
    return p1