Add Two Numbers

 

Add Two Numbers

Medium

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.

PYTHON SOLUTION

# Definition for singly-linked list.

# class ListNode:

#     def __init__(self, val=0, next=None):

#         self.val = val

#         self.next = next

class Solution:

    def summing(self,val1=0,val2=0):

        sumval=(val1+val2)

        rem=0

        if sumval/10 >=1.0:

            return sumval%10,sumval//10

        return sumval,rem

    

    def addTwoNumbers(self, l1: Optional[ListNode], l2: Optional[ListNode]) -> Optional[ListNode]:

        listsum=[]

        rem=0

        head=temp=ListNode(0)

        while l1 or l2:

            if l1 and l2:

                sumval,rem=self.summing(l1.val,l2.val+rem)

                l1,l2=l1.next,l2.next

            elif l1:

                sumval,rem=self.summing(l1.val+rem)

                l1=l1.next

            else:

                sumval,rem=self.summing(l2.val+rem)

                l2=l2.next

            temp.next= ListNode(sumval)

            temp=temp.next

        if rem:

            temp.next= ListNode(rem)

        return head.next