🚧 Add Two Numbers

Author: João Pedro Limão

leetcode/README.md

@@ -25,5 +25,5 @@ A repository to store leetcode solved problems.
 
 | Number | Title | Tags | Status | Solution |
 |--------|----------------------|-----------------------------------------------------------------------------------------|----------------|------------------------------------------------------------------------------------------------------------|
-| 36 | Valid Sudoku  | `Array` `Hash Table` `Matrix` | :construction: | [File](https://github.com/johnazedo/interview-questions/blob/main/leetcode/medium/valid_sudoku.go) |
+| 02 | Add Two Numbers | `Linked List` `Math` `Recursion` | :construction: | [File](https://github.com/johnazedo/interview-questions/blob/main/leetcode/medium/add_two_numbers.cpp) |
 

leetcode/medium/add_two_numbers.cpp

@@ -0,0 +1,65 @@
+#include "../data_structures.h"
+#include <bits/stdc++.h>
+
+using namespace std;
+
+/*
+ * Number: 02
+ * Difficult: Medium
+ * Link: https://leetcode.com/problems/add-two-numbers/
+ * Tags: Linked List, Math, Recursion
+ */ 
+
+class AddTwoNumbers {
+public:
+ /*
+ * Time complexity: O(N)
+ * Space complexity: O(N)
+ * 
+ * Time beats: 84.96%
+ * Space beats: 95.5%
+ */
+ ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
+ return helper(l1, l2);
+ }
+
+ ListNode* helper(ListNode* l1, ListNode* l2, int has_one = 0) {
+ int sum, number, up;
+
+ if(l1 == NULL && l2 == NULL && has_one == 0) {
+ return NULL;
+ }
+
+ if(l1 == NULL && l2 == NULL && has_one != 0) {
+ l1 = new ListNode(has_one, NULL);
+ return l1;
+ }
+
+ if(l1 == NULL) {
+ sum = l2->val + has_one;
+ l1 = new ListNode(0, NULL); 
+ }
+
+ if(l2 == NULL) {
+ sum = l1->val + has_one;
+ l2 = new ListNode(0, NULL); 
+ }
+
+ if(l1 != NULL && l2 != NULL) {
+ sum = l1->val + l2->val + has_one;
+ }
+
+ if(sum >= 10) {
+ number = sum % 10;
+ up = 1;
+ } else {
+ number = sum;
+ up = 0;
+ }
+
+ l1->val = number;
+ l1->next = helper(l1->next, l2->next, up);
+
+ return l1;
+ }
+};