0002.两数相加.py

#
# @lc app=leetcode.cn id=2 lang=python3
#
# [2] 两数相加
#
# https://leetcode-cn.com/problems/add-two-numbers/description/
#
# algorithms
# Medium (36.08%)
# Likes:    3625
# Dislikes: 0
# Total Accepted:    285.7K
# Total Submissions: 788.5K
# Testcase Example:  '[2,4,3]\n[5,6,4]'
#
# 给出两个 非空 的链表用来表示两个非负的整数。其中，它们各自的位数是按照 逆序 的方式存储的，并且它们的每个节点只能存储 一位 数字。
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# 如果，我们将这两个数相加起来，则会返回一个新的链表来表示它们的和。
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# 您可以假设除了数字 0 之外，这两个数都不会以 0 开头。
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# 示例：
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# 输入：(2 -> 4 -> 3) + (5 -> 6 -> 4)
# 输出：7 -> 0 -> 8
# 原因：342 + 465 = 807
# 
# 
#

# @lc code=start
# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
        tmp = ListNode(0)
        curr = tmp
        carry = 0
        while (l1 != None or l2 != None):
            x = l1.val if l1 != None else 0
            y = l2.val if l2 != None else 0
            sum = carry + x + y
            carry = sum // 10
            curr.next = ListNode(sum % 10)
            curr = curr.next
            if (l1 != None):
                l1 = l1.next
            if (l2 != None):
                l2 = l2.next
        if carry > 0:
            curr.next = ListNode(1)
        return tmp.next

# @lc code=end