002.两数相加

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.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 0 -> 8        342+465 = 807

• 题目描述：输入两个非空单链表，链表的每个结点的值是一个1位数整数，两个链表都是一个大整数每一位的逆序排序，求这两个链表代表的整数的和的链表值；

• 思路：​1. 获取到两个数 然后相加 再新建list写入。2.每位想加时候考虑进位标志位​

def addTwoNumbers(L1,L2):
  move = 0
  while L1:
    numOfL1 = L1.val * 10**move
    move += 1
    L1 = L1.next
  move = 0
  while L2:
    numOfL2 = L2.val * 10**move
    move += 1
    L2 = L2.next
  final = numOfL1 + numOfL2
  h = m = ListNode(0)
  if not final:
    return h
  while final:
    m.next = ListNode(final % 10)
    final = final/10
    m = m.next  # m.next 默认为空
  return h.next

# 带进位标志位的 函数 挺好
def addTwoNumbers(L1,L2):
  if L1 is None:
    return L2
  if L2 is None:
    return L1
  tmp = ListNode(0) # 最终要用的
  res = tmp
  flag = 0 #进位标记位
  while L1 or L2:
    tmpsum = 0
    if L1:
      tmpsum = L1.val
      L1 = L1.next
    if L2:
      tmpsum += L2.val
      L2 = L2.next
    tmpres = ((tmpsum + flag) % 10) # 余数
    flag = ((tmpsum + flag) // 10) # 进位
    res.next = ListNode(tmpres)
    res = res.next
  if flag:
    res.next = ListNode(1)
  res = tmp.next
  return res