fix: clang-tidy warnings

data_structures/reverse_a_linked_list.cpp

@@ -18,9 +18,9 @@
  * completion of an iteration.
  * Graphic Explanation:https://bit.ly/3nbVrFe
  */
-#include <iostream>      /// for I/O operations
-#include <memory>        /// for dynamic memory
-#include <cassert>       /// for assert
+#include <cassert>   /// for assert
+#include <iostream>  /// for I/O operations
+#include <memory>    /// for dynamic memory
 
 /**
  * @namespace data_structures
@@ -35,11 +35,10 @@ namespace linked_list {
 /**
  * A Node class containing a value and pointer to another link
  */
-class Node
-{
-public:
-int val;              /// value of the current link
-Node *next;          /// pointer to the next value on the list
+class Node {
+ public:
+    int val;     /// value of the current link
+    Node *next;  /// pointer to the next value on the list
 };
 
 /**
@@ -47,7 +46,7 @@ Node *next;          /// pointer to the next value on the list
  */
 class list {
  private:
-    Node *head{nullptr};   // link before the actual first element
+    Node *head = nullptr;  // link before the actual first element
  public:
     /**
      * List constructor. Initializes the first link.
@@ -55,7 +54,7 @@ class list {
     list() {
         // Initialize the first link
     }
-
+    bool isEmpty();
     void insert(int32_t new_elem);
     void reverseList();
     void display();
@@ -63,18 +62,29 @@ class list {
     int last();
 };
 
-
+/**
+ * function checks if list is empty
+ * @returns true if list is empty
+ * @returns false if list is not empty
+ */
+bool list::isEmpty() {
+    if (head == nullptr) {
+        return true;
+    } else {
+        return false;
+    }
+}
 
 /**
  * function adds new element to the end of the list
  * @param new_elem to be added to the end of the list
  */
 void list::insert(int32_t n) {
-   Node *new_node = new Node();
+    Node *new_node = new Node();
     Node *temp = nullptr;
     new_node->val = n;
     new_node->next = nullptr;
-    if (head == nullptr) {
+    if (isEmpty()) {
         head = new_node;
     } else {
         temp = head;
@@ -86,11 +96,11 @@ void list::insert(int32_t n) {
 }
 
 /**
- * function reverseList for reversing the  list 
+ * function reverseList for reversing the  list
  * @brief Using current,previous and next pointer.
  * @returns 'void'
  */
-void list:: reverseList() {
+void list::reverseList() {
     Node *curr = head;
     Node *prev = nullptr, *next_node = nullptr;
     while (curr != nullptr) {
@@ -107,24 +117,30 @@ void list:: reverseList() {
  * @returns 'int n'
  * @brief returns the first element in the list
  */
-int list::top()
-{
-    int n=head->val;
-    return n;
+int list::top() {
+    if (!isEmpty()) {
+        int n = head->val;
+        return n;
+    }
+    else
+    return 0;
+    
 }
 /**
  * function to find the last element of the list
  *  @returns 'int t->val'
  *  @brief returns the last element of the list
  */
-int list::last()
-{
-    Node *t=head;
-    while(t->next!=nullptr)
-    {
-        t=t->next;
+int list::last() {
+    if (!isEmpty()) {
+        Node *t = head;
+        while (t->next != nullptr) {
+            t = t->next;
+        }
+        return t->val;
     }
-    return t->val;
+    else return 0;
+    
 }
 
 /**
@@ -132,15 +148,16 @@ int list::last()
  * @returns 'void'
  */
 void list::display() {
-    Node *node=head;
-    while (node != nullptr) {
-        std::cout << node->val << "\t";
-        node = node->next;
+    if (!isEmpty()) {
+        Node *node = head;
+        while (node != nullptr) {
+            std::cout << node->val << "\t";
+            node = node->next;
+        }
+        std::cout << std::endl;
     }
-    std::cout << std::endl;
 }
 
-
 }  // namespace linked_list
 }  // namespace data_structures
 
@@ -150,8 +167,8 @@ void list::display() {
  */
 static void test() {
     data_structures::linked_list::list L;
-  // 1st test
-   
+    // 1st test
+
     L.insert(11);
     L.insert(12);
     L.insert(15);
@@ -159,14 +176,13 @@ static void test() {
     L.insert(12);
     L.insert(20);
     L.insert(18);
-    assert(L.top()==11);
-    assert(L.last()==18);
+    assert(L.top() == 11);
+    assert(L.last() == 18);
     L.reverseList();
-    //Reversal Testing
-    assert(L.top()==18);
-    assert(L.last()==11);
+    // Reversal Testing
+    assert(L.top() == 18);
+    assert(L.last() == 11);
     std::cout << "Passed" << std::endl;
-  
 }
 
 /**
@@ -174,6 +190,6 @@ static void test() {
  * @returns 0 on exit
  */
 int main() {
-    test();  //run self-test implementations
+    test();  // run self-test implementations
     return 0;
 }