Algoverse_adesh_46

'''

class Node:
    def __init__(self, data):   # data -> value stored in node
        self.data = data
        self.next = None
'''

class Solution:
    def addOne(self,head):
        #Returns new head of linked List.


        if not head:
            return None
        carry = 1
        new = self.rev(head)
        temp =new
        while temp:
            val = temp.data + carry
            temp.data = val%10
            carry = val//10
            temp = temp.next
        head = self.rev(new)
        if carry:
            new = Node(carry)
            new.next=head
            return new
        return head

    def rev(self,head):
        if not head or not head.next:
            return head
        prev = None
        curr = head
        while curr:
            f = curr.next
            curr.next = prev
            prev = curr
            curr = f
        return prev