GFG PTOD | 22 Jan 2025 | Add Number Linked Lists

class Solution {
  public:
    Node* reverseList(struct Node* head) {
       struct Node* cur = head, *prev = NULL, *next = NULL;
        while(cur != NULL) {
            next = cur->next;
            cur->next = prev;
            prev = cur;
            cur = next;
        }
        return prev;
    }
    
    Node* removeZero(struct Node* head) {
        while(head != NULL && head->data == 0)
            head = head->next;
        return head;
    }
    
    Node* addTwoLists(Node* num1, Node* num2) {
        // code here
        num1 = removeZero(num1);
        num2 = removeZero(num2);
        num1 = reverseList(num1);
        num2 = reverseList(num2);
        Node *ret = NULL, *cur=NULL;
        int carry = 0;
        
        while(num1 || num2 || carry != 0) {
            int sum = carry;
            if(num1) {
                sum += num1->data;
                num1 = num1->next;
            }
            if(num2) {
                sum += num2->data;
                num2 = num2->next;
            }
            carry = sum/10;
            Node *tmp = new Node(sum % 10);
            if(ret == NULL) {
                ret = tmp;
                cur = tmp;
            } else {
                cur->next = tmp;
                cur = cur->next;
            }
        }
        return reverseList(ret);
    }
};