Linked-List

Q1: Add Two Numbers

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* nxt = new ListNode();
        ListNode* root = nxt;
        int quotient = 0; 
        
        while(l1 != nullptr && l2 != nullptr) {
            int sum = l1 -> val + l2 -> val + quotient;
            nxt -> next = new ListNode(sum % 10);
            nxt = nxt->next;
            quotient = sum / 10;
            l1 = l1->next;
            l2 = l2->next;
        }

        if(l1 != nullptr) {
                while(l1 != nullptr) {
                int sum = l1 -> val + quotient;
                nxt -> next = new ListNode(sum % 10);
                nxt = nxt->next;
                quotient = sum / 10;
                l1 = l1->next;
            }
        }
        else if(l2 != nullptr) {
                while(l2 != nullptr) {
                int sum = l2 -> val+quotient;
                nxt -> next = new ListNode(sum % 10 );
                nxt = nxt->next;
                quotient = sum / 10;
                l2 = l2->next;
            }
        }
        if(quotient > 0)
            nxt -> next = new ListNode(quotient);
        return root -> next; 
    }
};