Reversing a linked list in python

Question

I am asked to reverse a which takes head as parameter where as head is a linked list e.g.: 1 -> 2 -> 3 which was returned from a function already defined I tried to implemen

Answer 1

Here is the whole thing in one sheet. Contains the creation of a linked list, and code to reverse it.

Includes an example so you can just copy and paste into an idle .py file and run it.

class Node(object):
    def __init__(self, value, next=None): 
        self.value = value                
        self.next = next                  


def reverse(head):
    temp = head
    llSize = 0
    while temp is not None:
        llSize += 1
        temp = temp.next
    for i in xrange(llSize-1,0,-1):
        xcount = 0
        temp = head
        while (xcount != i):
            temp.value, temp.next.value = temp.next.value, temp.value
            temp = temp.next
            xcount += 1
    return head


def printnodes(n):
    b = True
    while b == True:
        try:
            print n.value
            n = n.next
        except:
            b = False

n0 = Node(1,Node(2,Node(3,Node(4,Node(5,)))))
print 'Nodes in order...'
printnodes(n0)
print '---'
print 'Nodes reversed...'
n1 = reverse(n0)
printnodes(n1)