C++ Stack Exercises: Reverse a stack (using a dynamic array) elements

Last update on December 20 2024 12:25:40 (UTC/GMT +8 hours)

Write a C++ program that reverses the stack (using a dynamic array) elements.

Test Data:
Input the size of the stack: 8
Input some elements onto the stack:
Stack elements are: 4 7 5 3 1
Reverse the said stack elements:
Stack elements are: 1 3 5 7 4

Sample Solution:

C++ Code:

#include <iostream>

using namespace std;

// Class representing a Stack
class Stack {
public:
    int top;        // Index of top element
    int capacity;   // Maximum size of the stack
    int* arra;      // Pointer to the array storing elements

    // Constructor to initialize the stack with a given size
    Stack(int size) {
        arra = new int[size]; // Allocate memory for the stack array
        top = -1;             // Initialize top index to -1 (empty stack)
        capacity = size;      // Set the maximum capacity of the stack
    }

    // Function to push an element onto the stack
    bool push(int x) {
        if (isFull()) {
            cout << "Stack is full" << endl; // Display overflow message if the stack is full
            return false;
        }
        // Add element to array by incrementing top index
        arra[++top] = x;
        return true;
    }

    // Function to pop an element from the stack
    int pop() {
        if (isEmpty()) {
            cout << "Stack underflow" << endl; // Display underflow message if the stack is empty
            return 0;
        }
        // Return the top element and decrement the index of the top element
        return arra[top--];
    }

    // Function to peek the top element of the stack without removing it
    int peek() {
        if (isEmpty()) {
            cout << "Stack is empty" << endl; // Display message if the stack is empty
            return 0;
        }
        // Return the top element without modifying the top index
        return arra[top];
    }

    // Function to check if the stack is empty
    bool isEmpty() {
        // Stack is empty if top index is -1
        return (top < 0);
    }

    // Function to check if the stack is full
    bool isFull() {
        // Stack is full if top index is equal to capacity - 1
        return (top >= capacity - 1);
    }

    // Function to display the elements of the stack
    void display() {
        if (top < 0) {
            cout << "Stack is empty" << endl; // Display message if the stack is empty
            return;
        }
        cout << "\nStack elements are: ";
        for (int i = top; i >= 0; i--)
            cout << arra[i] << " "; // Display the elements of the stack
        cout << endl;
    }
};

// Function to sort the elements of a stack in descending order
void sort_stack(int* stackArray, int& top) {
    int temp;
    for (int i = 0; i <= top; i++) {
        for (int j = i + 1; j <= top; j++) {
            if (stackArray[j] > stackArray[i]) {
                // Swap elements to arrange them in descending order
                temp = stackArray[i];
                stackArray[i] = stackArray[j];
                stackArray[j] = temp;
            }
        }
    }
}

int main() {
    int size;
    cout << "Input the size of the stack: ";
    cin >> size; // Take input for the size of the stack
    Stack stk(size); // Create a stack of the given size
    cout << "\nInput some elements onto the stack:";
    stk.push(1);
    stk.push(3);
    stk.push(5);
    stk.push(7);
    stk.push(4);    
    stk.display(); // Display the elements of the stack
    cout << "\nAfter sorting the said stack elements:";
    sort_stack(stk.arra, stk.top); // Sort the stack elements in descending order
    stk.display(); // Display the sorted elements of the stack
    return 0;
}

Sample Output:

Input the size of the stack: 8

Input some elements onto the stack:
Stack elements are: 4 7 5 3 1

Reverse the said stack elements:
Stack elements are: 1 3 5 7 4

Input 2 more elements onto the said stack:

Stack elements are: 40 70 1 3 5 7 4

Reverse the said stack elements:
Stack elements are: 4 7 5 3 1 70 40

Flowchart:

CPP Code Editor:

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Previous C++ Exercise: Sort a stack (using a dynamic array) elements.
Next C++ Exercise: Middle element of a stack (using a dynamic array).