leetCode解题记录2

给出两个 非空 的链表用来表示两个非负的整数。其中，它们各自的位数是按照 逆序 的方式存储的，并且它们的每个节点只能存储 一位 数字。

如果，我们将这两个数相加起来，则会返回一个新的链表来表示它们的和。

您可以假设除了数字 0 之外，这两个数都不会以 0 开头。

输入：(2 -> 4 -> 3) + (5 -> 6 -> 4)
输出：7 -> 0 -> 8
原因：342 + 465 = 807

其实这题比较简单，无非是两个链表之间同层级的数字相加，唯一要注意的就是如果相加之后数字大于10，需要往下一级+1，当前级数是个位的那个数字。基本也是一个循环可以解决的。再注意处理下，如果一个链表长度长于另一个链表时的边界处理，其余就没啥了。

const addTwoNumbers = (l1, l2) => {
    let l3 = null
    let cache = 0
    let tens = 0
    while (l1 || l2) {
 let total = 0
 if (l1) {
     let l1Head = l1.val
     total += l1Head
     l1 = l1.next
 }
 if (l2) {
     let l2Head = l2.val
     total += l2Head
     l2 = l2.next
 }
 total += tens
 if (total >= 10) {
     total -= 10
     tens = 1
 } else {
     tens = 0
 }
 let node = new ListNode(total)
 if (cache) {
     cache.next = node
     cache = node
 } else {
     l3 = node
     cache = l3
 }
    }
    if (tens === 1) {
 cache.next = new ListNode(1)
    }
    return l3
}

class ListNode {
    val: number
    next: ListNode | any
    constructor(value: number) {
 this.val = value
 this.next = null
    }
}
 

const addTwoNumbers = (l1: ListNode, l2: ListNode) => {
    let l3: null | ListNode = null
    let cache: ListNode | null = null
    let tens: number = 0
    while (l1 || l2) {
 let total: number = 0
 if (l1) {
     let l1Head = l1.val
     total += l1Head
     l1 = l1.next
 }
 if (l2) {
     let l2Head = l2.val
     total += l2Head
     l2 = l2.next
 }
 total += tens
 if (total >= 10) {
     total -= 10
     tens = 1
 } else {
     tens = 0
 }
 let node = new ListNode(total)
 if (cache) {
     cache.next = node
     cache = node
 } else {
     l3 = node
     cache = l3
 }
    }
    if (tens === 1) {
 cache.next = new ListNode(1)
    }
    return l3
}

# 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:
 """
 :type l1: ListNode
 :type l2: ListNode
 :rtype: ListNode
 """
 l3 = None
 cache = 0
 tens = 0
 while l1 or l2:
     total = 0
     if l1:
  l1Head = l1.val
  total = total + l1Head
  l1 = l1.next
     if l2:
  l1Head = l2.val
  total = total + l1Head
  l2 = l2.next
     total = total + tens
     if total >= 10:
  total = total - 10
  tens = 1
     else:
  tens = 0
     node = ListNode(total)
     if cache:
  cache.next = node
  cache = node
     else:
  l3 = node
  cache = l3
 if tens == 1:
     cache.next = ListNode(1)
 return l3