2. Add Two Numbers
1. 题目
You are given two non-empty linked lists representing two non-negative integers. 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.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.
Example:
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.
2.思路
本题其实没有什么巧妙的算法。主要是两个链表的数字相加，注意边界条件以及进位就好了
3. 实现
# 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
"""
jinw = 0
r = ListNode(0)
ret = r
while True:
if l1 != None and l2 != None:
ret.val = l1.val + l2.val + jinw
elif l1 == None and l2 != None:
ret.val = l2.val + jinw
elif l2 == None and l1 != None:
ret.val = l1.val + jinw
elif jinw != 0 and l2 == None and l1 == None:
ret.val = jinw
if ret.val >= 10 :
jinw = ret.val /10
ret.val = ret.val % 10
else:
jinw = 0
if ( l1 == None and l2 == None and jinw == 0 ):
break
if l1 is not None or jinw != 0 :
if l1 is None :
pass
else:
l1 = l1.next
if l2 is not None or jinw != 0 :
if l2 is None :
pass
else:
l2 = l2.next
if jinw != 0 or l1 != None or l2 !=None :
ret.next = ListNode(0)
ret = ret.next
return r