add_two_number_leetcode.cpp

add_two_number_leetcode.cpp

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
       int carry = 0;
        ListNode* current = new ListNode(0);
        ListNode* start = current;
        // Loop 
        while(l1 || l2){
          int x1 = l1?l1->val:0;  
          int x2 = l2?l2->val:0;  
          int sum = carry + x1 + x2;
          carry = sum/10;
          current->next = new ListNode(sum%10);
          current = current->next;
          // Special condition when same no. of element and carry  
           if(l1){
               l1 = l1->next;
           }
          if(l2){
               l2 = l2->next;
           }
        }
        
        if(carry>0){
            current->next = new ListNode(carry);
            current = current->next;
        }
        
        current->next = NULL;
        return start->next;
    }
};