leetcood学习笔记-2-两数相加

题目描述：

方法一：

# 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:
        cur_l1 = l1
        cur_l2 = l2
        cur = ListNode(0)
        head = cur
        flag = 0
        while cur_l1 != None or cur_l2 != None:
            value = 0
            value += flag
            if cur_l1 != None:
                value += cur_l1.val
            if cur_l2 != None:
                value += cur_l2.val
            new_node = ListNode(0)
            cur.next = new_node
            cur = cur.next
            cur.val = value % 10
            flag = value // 10
            if cur_l1 != None:
                cur_l1 = cur_l1.next
            if cur_l2 != None:
                cur_l2 = cur_l2.next

        if flag != 0:
            new_node = ListNode(0)
            cur.next = new_node
            cur = cur.next
            cur.val = flag
        return head.next