leetcode 2.Add Two Numbers

题目描述

https://leetcode.com/problems/add-two-numbers/

解决方法

# 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
        """
        l1_str = ""
        l2_str = ""
        while l1:
            l1_str += str(l1.val)
            l1 = l1.next
        while l2:
            l2_str += str(l2.val)
            l2 = l2.next
        
        int_l1 = int(l1_str[::-1])
        int_l2 = int(l2_str[::-1])
        l3_str = str(int_l1 + int_l2)
        
        
        node = None
        i = 0
        while i < len(l3_str):
            
            l3 = ListNode(l3_str[i])
            l3.next = node
            node = l3
            i = i+1
        return l3

注意我这里运算出来的结果是l3_str 正序的，所以在l3是倒序指向