C++ Stack Exercises: Sort the stack (using a Deque) elements

Last update on April 14 2025 12:47:57 (UTC/GMT +8 hours)

29. Sort the Elements of a Deque-Based Stack

Write a C++ program that sorts the stack (using a Deque) elements.

Test Data:
Create a stack object:
Input and store (using Deque) some elements onto the stack:
Stack elements are: 1 3 2 6 5 -1 0
Sort the stack items in ascending order:
Stack elements are: -1 0 1 2 3 5 6

Sample Solution:

C++ Code:

#include <iostream>
#include <deque>
#include<algorithm>

using namespace std;

class Stack {
private:
    deque<int> elements; // Deque to store elements

public:
    // Function to add an element to the stack
    void push(int element) {
        elements.push_back(element); // Add element to deque
    }

    // Function to remove an element from the stack
    void pop() {
        if (elements.empty()) {
            cout << "Stack underflow" << endl; // Display underflow message if deque is empty
        } else {
            elements.pop_back(); // Remove last element from deque
        }
    }

    // Function to get the top element of the stack
    int top() {
        if (elements.empty()) {
            cout << "Stack is empty" << endl; // Display empty message if deque is empty
            return 0;
        } else {
            return elements.back(); // Return last element in deque
        }
    }

    // Function to check if the stack is empty
    bool empty() {
        return elements.empty(); // Check if deque is empty
    }

    // Function to sort elements in the stack in ascending order
    void sort_elements() {
        if (elements.empty()) {
            cout << "Stack is empty" << endl; // Display empty message if deque is empty
            return;
        }
        sort(elements.begin(), elements.end()); // Sort elements in ascending order
    }

    // Function to display the elements in the stack
    void display() {
        deque<int> d = elements;
        if (d.empty()) {
            cout << "Stack is empty" << endl; // Display empty message if deque is empty
            return;
        }
        cout << "Stack elements are: ";
        for (int i = 0; i < d.size(); i++) {
            cout << d[i] << " "; // Display the elements in the deque
        }
        cout << endl;
    }
};

int main() {
    Stack stack;
    //Initialize a stack 
    cout << "Create a stack object:\n";
    cout << "\nInput and store (using Deque) some elements onto the stack:\n";
    stack.push(1);
    stack.push(3);
    stack.push(2);
    stack.push(6);
    stack.push(5);
    stack.push(-1);
    stack.push(0);
    stack.display();
    cout << "\nSort the stack items in ascending order:\n";
    stack.sort_elements();
    stack.display();
    cout << "\nRemove two elements from the stack:\n";
    stack.pop();
    stack.pop();
    stack.display();
    cout << "\nInput three elements onto the stack:\n";
    stack.push(4);
    stack.push(7);
    stack.push(-2);
    stack.display();
    cout << "\nSort the said items in ascending order:\n";
    stack.sort_elements();
    stack.display();
    return 0;
}

Sample Output:

Create a stack object:

Input and store (using Deque) some elements onto the stack:
Stack elements are: 1 3 2 6 5 -1 0 

Sort the stack items in ascending order:
Stack elements are: -1 0 1 2 3 5 6 

Remove two elements from the stack:
Stack elements are: -1 0 1 2 3 

Input three elements onto the stack:
Stack elements are: -1 0 1 2 3 4 7 -2 

Sort the said items in ascending order:
Stack elements are: -2 -1 0 1 2 3 4 7 

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program to sort the elements of a deque-based stack in ascending order using an auxiliary deque.
• Develop a C++ program that implements a stack using a deque and rearranges its elements using a custom sort algorithm.
• Design a C++ program to create a deque-based stack and sort its contents while preserving the deque structure.
• Implement a C++ program to build a stack with a deque and perform sorting by iteratively repositioning the elements.

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Previous C++ Exercise: Implement a stack using a Deque with push, pop operations.
Next C++ Exercise: Reverse the stack (using a Deque) elements.