add-two-numbers.py

[sanisapascaline]

Definition for singly-linked list.

class ListNode(object):
def init(self, x):
self.val = x
self.next = None

class Solution(object):
# def addTwoNumbers(self, l1, l2):
# """
# :type l1: ListNode
# :type l2: ListNode
# :rtype: ListNode
# """
# last = 0
# head = prev = None
# while True:
# if l2 is None and l1 is None and last == 0:
# break
# val = last
# if l2 is not None:
# val += l2.val
# l2 = l2.next
# if l1 is not None:
# val += l1.val
# l1 = l1.next
# if val >= 10:
# val = val % 10
# last = 1
# else:
# last = 0
# current = ListNode(val)
# if prev is None:
# head = current
# else:
# prev.next = current
# prev = current
# return head

def addTwoNumbers(self, l1, l2):
    carry = 0
    # dummy head
    head = curr = ListNode(0)
    while l1 or l2:
        val = carry
        if l1:
            val += l1.val
            l1 = l1.next
        if l2:
            val += l2.val
            l2 = l2.next
        curr.next = ListNode(val % 10)
        curr = curr.next
        carry = val / 10
    if carry > 0:
        curr.next = ListNode(carry)
    return head.next