问题描述
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
代码实现
# 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
"""
headNode = ListNode(0)
point = headNode
sum = 0
while (l1 != None) or (l2 != None) :
if(l1 != None) :
sum = sum + l1.val
l1 = l1.next
if(l2 != None) :
sum = sum + l2.val
l2 = l2.next
newNode = ListNode(sum % 10)
point.next = newNode
point = point.next
sum = sum//10
if sum > 0 :
newNode = ListNode(sum)
point.next = newNode
return headNode.next
经验总结
- 定义新的头结点（headNode）有利于返回和控制整个链表
- 两个if判断是否为None，简化了代码结构，避免了多次分类讨论
- 临时变量定义新sum，随机记录
