445. Add Two Numbers II ——while s1 or s2 or carry 题目再简单也要些测试用例
You are given two linked lists representing two non-negative numbers. The most significant digit comes first 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.
Follow up:
What if you cannot modify the input lists? In other words, reversing the lists is not allowed.
Example:
Input: (7 -> 2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 8 -> 0 -> 7
# 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 Input: (7 -> 2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 8 -> 0 -> 7 7->2->4->3 5->6->4 =------------- 7->7->0->7 ->1 """ s1,s2 = [],[] p1,p2 = l1,l2 while p1: s1.append(p1.val) p1 = p1.next while p2: s2.append(p2.val) p2 = p2.next carry = 0 fake_head = ListNode(None) while s1 or s2 or carry: v1 = s1.pop() if s1 else 0 v2 = s2.pop() if s2 else 0 val = v1 + v2 + carry if val >= 10: val -= 10 carry = 1 else: carry = 0 head = ListNode(val) head.next = fake_head.next fake_head.next = head return fake_head.next