Add two linked lists leetcode

LeetCode Add Two Numbers

Problem statement

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.

Problem statement taken from: //leetcode.com/problems/add-two-numbers

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 val - Move l1 to point next node l1 = l1->next - if [ l2 != nil ] - Add l2-> val to sum as sum += l2->val - Move l2 to point next node l2 = l2->next - Initialize new ListNode with last digit of sum new ListNode[ sum % 10 ] - Assign current node next to the new ListNode created above - current->next = new ListNode[ sum % 10 ] - Set current to current->next - Set sum = sum / 10. sum / 10 will be 0 for sum < 10 and 1 for sum >= 10 - Check if sum > 9, if so append a new node with digit 1 to current node. - Return result->next since result is still pointing to current's first position.

C++ solution

class Solution { public: ListNode* addTwoNumbers[ListNode* l1, ListNode* l2] { int sum = 0; ListNode result[0]; ListNode *current = &result; while[l1 || l2]{ if[l1]{ sum += l1->val; l1 = l1->next; } if[l2]{ sum += l2->val; l2 = l2->next; } current->next = new ListNode[sum % 10]; current = current->next; sum = sum / 10; } if[sum > 0]{ current->next = new ListNode[sum / 10]; } return result.next; } };

Golang solution

func addTwoNumbers[l1 *ListNode, l2 *ListNode] *ListNode { sum := 0 current := new[ListNode] result := current for l1 != nil || l2 != nil { if l1 != nil { sum = sum + l1.Val l1 = l1.Next } if l2 != nil { sum = sum + l2.Val l2 = l2.Next } current.Next = &ListNode{sum % 10, nil} current = current.Next sum = sum / 10 } if sum > 0 { current.Next = &ListNode{sum, nil} } return result.Next }