refactor: create a random function

.clang-tidy

-Checks: 'cppcoreguidelines-*,google-*,modernize-use-nullptr,performance-*,portability-*,readability-*'
+Checks: 'cppcoreguidelines-*,google-*,modernize-use-nullptr,performance-*,portability-*,readability-*,-cppcoreguidelines-owning-memory'
 WarningsAsErrors: true
 FormatStyle: google

src/graph.cpp

@@ -12,6 +12,15 @@
 
 using namespace std;
 
+/**
+ * Generate a random number between 0 and max
+ * @param max - the maximum value
+ * @return the random number
+ */
+int random(int max) {
+  return static_cast<int>(arc4random() % max);
+}
+
 /**
  * Generate a random string of a given length
  * @param length - the length of the string
@@ -26,7 +35,7 @@ string RandomString(int length) {
       'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
 
   for (int i = 0; i < length; ++i) {
-    result += alphabet.at(rand() % alphabet_size);
+    result += alphabet.at(random(alphabet_size));
   }
 
   return result;
@@ -57,7 +66,7 @@ std::vector<std::string> split(const std::string &str, char delimiter) {
  */
 template <typename T>
 T GetRandomElement(const std::set<T> &elements) {
-  return *std::next(elements.begin(), rand() % elements.size());
+  return *std::next(elements.begin(), random(elements.size()));
 }
 
 Graph::Graph(){};
@@ -173,7 +182,6 @@ Graph::Graph(const string &filename) {
 
 Graph *Graph::GenerateRandomGraph(int n_states, int n_transitions,
                                   int n_labels) {
-  srand(time(nullptr));  // seed the random number generator
   Graph *graph = new Graph();
 
   // create states
@@ -236,7 +244,7 @@ Graph *Graph::GenerateRandomGraph(int n_states, int n_transitions,
   // add additional transitions randomly
   while (counter_transitions < n_transitions) {
     // choose a random source node
-    int source_id = rand() % n_states;
+    int source_id = random(n_states);
     Node *source = graph->get_state(source_id);
 
     // Ensure the chosen transition label is unique for the current node
@@ -249,7 +257,7 @@ Graph *Graph::GenerateRandomGraph(int n_states, int n_transitions,
     used_labels[source].insert(label);
 
     // Choose a random target node
-    int target_id = rand() % n_states;
+    int target_id = random(n_states);
 
     // Add the transition
     graph->add_successor(source_id, target_id, label);