tags: leetcode
Introduce:
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 contains a single digit. Add the two numbers and return the sum as a linked list.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.
Example 1:
Input: l1 = [2,4,3], l2 = [5,6,4]
Output: [7,0,8]
Explanation: 342 + 465 = 807.
Example 2:
Input: l1 = [0], l2 = [0]
Output: [0]
Example 3:
Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
Output: [8,9,9,9,0,0,0,1]
Constraints:
- The number of nodes in each linked list is in the range [1, 100].
- 0 <= Node.val <= 9
- It is guaranteed that the list represents a number that does not have leading zeros.
tips:
- "while l1 or l2 or plus == 1" would cover all the statement.
class Solution:
def addTwoNumbers(self, l1: Optional[ListNode], l2: Optional[ListNode]) -> Optional[ListNode]:
head = ListNode(0)
cur = head
plus = 0
while l1 or l2 or plus == 1:
v1 = l1.val if l1 else 0
v2 = l2.val if l2 else 0
total = v1 + v2 + plus
plus = total // 10
l1 = l1.next if l1 else None
l2 = l2.next if l2 else None
cur.next = ListNode(total % 10)
cur = cur.next
return head.next
