Leetcode 2: Add Two Numbers
You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 –> 8
Analysis
It is a easy one. Pay attention to the carry-over.
Solution
Python codes
# 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
"""
if l1 == None:
return l2
elif l2 == None:
return l1
head = None
addup = 0
while l1 != None and l2 != None:
tv = (l1.val + l2.val + addup) % 10
addup = (l1.val + l2.val + addup) // 10
tl = ListNode(tv)
if head == None:
head = tl
pl = tl
else:
pl.next = tl
pl = tl
l1 = l1.next
l2 = l2.next
while l1 != None:
tv = (l1.val + addup) % 10
addup = (l1.val + addup) // 10
tl = ListNode(tv)
pl.next = tl
pl = tl
l1 = l1.next
while l2 != None:
tv = (l2.val + addup) % 10
addup = (l2.val + addup) // 10
tl = ListNode(tv)
pl.next = tl
pl = tl
l2 = l2.next
if addup > 0:
tl = ListNode(addup)
pl.next = tl
return head
