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Add Two NumbersAdd Two Numbers

admin 11月 13, 2020 0

Question

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.

Answer

这道题是两个数相加，只不过数是以链表的形式表示的。所以我们从低位向高位加，维护一个进位的变量即可。

# 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
        """
        root = n = ListNode(0)
        carry = 0
        while l1 or l2 or carry:
            v1 = v2 = 0
            if l1:
                v1 = l1.val
                l1 = l1.next
            if l2:
                v2 = l2.val
                l2 = l2.next
            carry, val = divmod(v1 + v2 + carry, 10)
            n.next = ListNode(val)
            n = n.next
        return root.next