C++ Stack Exercises: Reverse the elements of a stack (using a linked list)

C++ Stack: Exercise-18 with Solution

Write a C++ program to reverse the elements of a stack (using a linked list).

Test Data:
Input some elements onto the stack:
Stack elements are: 0 1 3 5 6
Display the reverse elements of the stack:
Stack elements are: 6 5 3 1 0

Sample Solution:

C++ Code:

#include <iostream>

using namespace std;

// Define the node structure for the linked list
struct Node {
    int data;
    Node* next;
};

class Stack {
private:
    //This variable keeps track of the stack size
    int size;  

public:
    // Top-of-stack pointer
    Node* top;
    // Constructor to initialize an empty stack
    Stack() {
        top = NULL; // Initialize top pointer to NULL for an empty stack
        size = 0; // Initialize the size of the stack to zero
    }

    // Function to push an element onto the stack
    void push(int x) {
        Node* new_Node = new Node(); // Create a new node
        new_Node->data = x; // Assign data to the new node
        new_Node->next = top; // Point the new node's next to the current top node
        top = new_Node; // Update top to the new node
        size++; // Increment the size of the stack
    }

    // Function to pop an element from the stack
    void pop() {
        if (top == NULL) {
            cout << "Stack is empty!" << endl; // Display message if the stack is empty
            return;
        }
        Node* temp = top; // Store the current top node
        top = top->next; // Move top to the next node
        size--; // Decrement the size of the stack
        delete temp; // Delete the previous top node
    }

    // Function to reverse the elements of the stack
    void reverseStack(Node** top) {
        if (*top == NULL) {
            cout << "Stack is empty." << endl; // Display message if the stack is empty
            return;
        }

        Node* prev = NULL;
        Node* curr = *top;
        Node* next = NULL;

        while (curr != NULL) {
            next = curr->next;
            curr->next = prev;
            prev = curr;
            curr = next;
        }

        *top = prev; // Update the top pointer with the reversed stack
    }

    // Function to display the elements of the stack
    void display() {
        if (top == NULL) {
            cout << "Stack is empty!" << endl; // Display message if the stack is empty
            return;
        }
        Node* temp = top; // Create a temporary node to traverse the stack
        cout << "Stack elements are: ";
        while (temp != NULL) {
            cout << temp->data << " "; // Display the data of each node
            temp = temp->next; // Move to the next node
        }
        cout << endl;
    }
};

int main() {
    Stack stk; // Create an object of Stack class
    cout << "Input some elements onto the stack:\n";
    stk.push(6);
    stk.push(5);
    stk.push(3);
    stk.push(1);
    stk.push(0);
    stk.display(); // Display the elements in the stack
    cout << "\nDisplay the reverse elements of the stack:\n";
    stk.reverseStack(&stk.top); // Reverse the stack elements
    stk.display(); // Display the reversed stack elements
    cout << "\nInput two more elements:\n";
    stk.push(35);
    stk.push(45);
    stk.display(); // Display the updated elements in the stack
    cout << "\nDisplay the reverse elements of the stack:\n";
    stk.reverseStack(&stk.top); // Reverse the stack elements again
    stk.display(); // Display the reversed stack elements
    return 0;
}

Sample Output:

Input some elements onto the stack:
Stack elements are: 0 1 3 5 6 

Display the reverse elements of the stack:
Stack elements are: 6 5 3 1 0 

Input two more elements:
Stack elements are: 45 35 6 5 3 1 0 

Display the reverse elements of the stack:
Stack elements are: 0 1 3 5 6 35 45

Flowchart:

CPP Code Editor:

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Previous C++ Exercise: Check the size and empty status of a stack (linked list).
Next C++ Exercise: Sort the elements of a stack (using a linked list).