Problem 2: ruby rewrite

problems/2-add-two-numbers/Makefile

@@ -1 +0,0 @@
-../template/Makefile

problems/2-add-two-numbers/lib.c

@@ -1,45 +0,0 @@
-#include <stdlib.h>
-#include "lib.h"
-
-struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {
-    struct ListNode* current = NULL;
-    struct ListNode* first_node = NULL;
-
-    int reminder = 0;
-    while (l1 != NULL || l2 != NULL || reminder != 0) {
-        // Read digits
-        int a = 0;
-        int b = 0;
-        if (l1 != NULL)
-            a = l1->val;
-        if (l2 != NULL)
-            b = l2->val;
-
-        // Move pointers to the next node
-        if (l1 != NULL)
-            l1 = l1->next;
-        if (l2 != NULL)
-            l2 = l2->next;
-
-        // Calculate the result
-        int digit = (a + b + reminder) % 10;
-        reminder = (a + b + reminder) / 10;
-
-        // Create the first node
-        if (current == NULL) {
-            current = malloc(sizeof(struct ListNode));
-            first_node = current;
-        }
-        // Create regular node
-        else {
-            current->next = malloc(sizeof(struct ListNode));
-            current = current->next;
-        }
-
-        // Save the result
-        current->val = digit;
-        current->next = NULL;
-    }
-    
-    return first_node;
-}

problems/2-add-two-numbers/lib.h

@@ -1,8 +0,0 @@
-#pragma once
-
-struct ListNode {
-    int val;
-    struct ListNode *next;
-};
-
-struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2);

problems/2-add-two-numbers/main.c

@@ -1,86 +0,0 @@
-#include <stdlib.h>
-#include <stdio.h>
-#include "lib.h"
-
-// Creates single node
-struct ListNode* mkNode(int val) {
-    struct ListNode* node = malloc(sizeof(struct ListNode));
-    node->val = val;
-    node->next = NULL;
-    return node;
-}
-
-// Creates linked list
-struct ListNode* mkList(int* nums, int length) {
-    struct ListNode* first = NULL;
-    struct ListNode* current = NULL;
-    for (int i=0; i<length; i++) {
-        // First node
-        if (current == NULL) {
-            current = mkNode(nums[i]);
-            first = current;
-        }
-        // Regular node
-        else {
-            current->next = mkNode(nums[i]);
-            current = current->next;
-        }
-    }
-    return first;
-}
-
-// Returns 1 if linked lists are equal.
-// Returns 0 otherwise.
-int cmpLists(struct ListNode* a, struct ListNode* b) {
-    while (a != NULL || b != NULL) {
-        // Both nodes exist
-        if (a == NULL || b == NULL)
-            return 0;
-
-        // Check values
-        if (a->val != b->val)
-            return 0;
-        
-        // Go to next node
-        a = a->next;
-        b = b->next;
-    }
-
-    return 1;
-}
-
-// Free allocated memory
-void freeLinkedList(struct ListNode* list) {
-    struct ListNode* current;
-    while (list != NULL) {
-        current = list;
-        list = list->next;
-        free(current);
-    }
-}
-
-int main() {
-    // First list
-    int a[] = {2, 4, 3};
-    struct ListNode* list_a = mkList(a, 3);
-
-    // Second list
-    int b[] = {5, 6, 4};
-    struct ListNode* list_b = mkList(b, 3);
-
-    // Expected sum
-    int c[] = {7, 0, 8};
-    struct ListNode* list_c = mkList(c, 3);
-
-    // Computed result
-    struct ListNode* res = addTwoNumbers(list_a, list_b);
-
-    printf("Test 1: %d\n", cmpLists(res, list_c));
-
-    freeLinkedList(list_a);
-    freeLinkedList(list_b);
-    freeLinkedList(list_c);
-    freeLinkedList(res);
-
-    return 0;
-}

problems/2-add-two-numbers/main.rb

@@ -0,0 +1,38 @@
+require_relative 'types'
+
+# @param {ListNode} l1
+# @param {ListNode} l2
+# @return {ListNode}
+def add_two_numbers(l1, l2)
+  reminder = 0
+  current = nil
+  first_node = nil
+
+  while !l1.nil? || !l2.nil? || reminder != 0
+    # Read digits
+    a = 0
+    b = 0
+    a = l1.val unless l1.nil?
+    b = l2.val unless l2.nil?
+
+    # Move pointers to the next node
+    l1 = l1.next unless l1.nil?
+    l2 = l2.next unless l2.nil?
+
+    # Calculate the result
+    digit = (a + b + reminder) % 10
+    reminder = (a + b + reminder) / 10
+
+    # Create the first node
+    if current.nil?
+      current = ListNode.new(digit)
+      first_node = current
+    # Create regular node
+    else
+      current.next = ListNode.new(digit)
+      current = current.next
+    end
+  end
+
+  first_node
+end

problems/2-add-two-numbers/test.rb

@@ -0,0 +1,20 @@
+require_relative 'main'
+require 'test/unit'
+
+class TestAddTwoNumbers < Test::Unit::TestCase
+  def test_case_1
+    a3 = ListNode.new(3)
+    a2 = ListNode.new(4, a3)
+    a1 = ListNode.new(2, a2)
+
+    b3 = ListNode.new(4)
+    b2 = ListNode.new(6, b3)
+    b1 = ListNode.new(5, b2)
+
+    c = add_two_numbers(a1, b1)
+
+    assert_equal(7, c.val)
+    assert_equal(0, c.next.val)
+    assert_equal(8, c.next.next.val)
+  end
+end

problems/2-add-two-numbers/types.rb

@@ -0,0 +1,8 @@
+# Definition for singly-linked list.
+class ListNode
+  attr_accessor :val, :next
+  def initialize(val = 0, _next = nil)
+    @val = val
+    @next = _next
+  end
+end