2. Add Two Numbers

2. Add Two Numbers

难度: Medium

刷题内容

原题连接

内容描述

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.

思路 1
- 时间复杂度: O(N)- 空间复杂度: O(N)

l1l2全部变成数字做加法再换回去呗,这是我们最直接的想法了

beats 54.35%

```python
class Solution:
def addTwoNumbers(self, l1, l2):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
# 获得 l1 和 l2 的 integer 表示
val1, val2 = [l1.val], [l2.val]

    while l1.next:
        val1.append(l1.next.val)
        l1 = l1.next
    while l2.next:
        val2.append(l2.next.val)
        l2 = l2.next

    # 求出 l1 和 l2 代表的数字
    num1 = ''.join([str(i) for i in val1[::-1]])
    num2 = ''.join([str(i) for i in val2[::-1]])

    # 得到 l1 和 l2 相加之和
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