C++ Stack Exercises: Find the minimum element in a stack (using an array)

Last update on April 14 2025 12:48:08 (UTC/GMT +8 hours)

7. Find the Minimum Element in an Array-Based Stack

Write a C++ program to find the minimum element in a stack (using an array).

Test Data:
Input some elements onto the stack:
Stack elements: 0 1 5 2 4 7
Minimum value: 0

Sample Solution:

C++ Code:

#include <iostream>

using namespace std;

#define MAX_SIZE 15 // Maximum size of stack

class Stack {
private:
    int top; // Index of top element
    int arr[MAX_SIZE]; // Array to store elements

public:
    Stack() {
        top = -1; // Initialize top index to -1 (empty stack)
    }

    bool push(int x) {
        if (isFull()) {
            cout << "Stack overflow" << endl; // Display message if stack is full
            return false; // Return false to indicate failure in pushing element
        }
        // Increment top index and add element to array
        arr[++top] = x; 
        return true; // Return true to indicate successful element addition
    }

    int pop() {
        if (isEmpty()) {
            cout << "Stack underflow" << endl; // Display message if stack is empty
            return 0; // Return 0 to indicate failure in popping element
        }
        // Return top element and decrement top index
        return arr[top--]; 
    }

    int peek() {
        if (isEmpty()) {
            cout << "Stack is empty" << endl; // Display message if stack is empty
            return 0; // Return 0 to indicate failure in peeking element
        }
        // Return top element without modifying top index
        return arr[top]; 
    }

    bool isEmpty() {
        // Stack is empty if top index is -1
        return (top < 0); 
    }

    bool isFull() {
        // Stack is full if top index is equal to MAX_SIZE - 1
        return (top >= MAX_SIZE - 1); 
    }

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

    int min() {
        if (isEmpty()) {
            // Return the maximum possible integer if the stack is empty    	
            return INT_MAX; 
        }
        int minVal = arr[0];
        for (int i = 1; i <= top; i++) {
            if (arr[i] < minVal) {
                // Update the minimum value if we find a smaller element    	
                minVal = arr[i]; 
            }
        }
        // Return the minimum value 
        return minVal;
    }
};

int main() {
    //Initialize the stack stk
    Stack stk; 
    cout << "Input some elements onto the stack:";
    stk.push(7);
    stk.push(4);
    stk.push(2);
    stk.push(5);
    stk.push(1);
    stk.push(0);
    stk.display(); 
     // Find the maximum value 
    int min_val = stk.min(); 
    cout << "\nMinimum value: " << min_val << endl; // Display the minimum value
    cout << "\nRemove two elements:";
    stk.pop();
    stk.pop();
    stk.display(); 
    cout << "\nInput two more elements";
    stk.push(-1);
    stk.push(10);
    stk.display();
    min_val = stk.min(); 
    cout << "\nMinimum value: " << min_val << endl; // Display the minimum value
    cout << endl;
    return 0;
}

Sample Output:

Input some elements onto the stack:
Stack elements: 0 1 5 2 4 7

Minimum value: 0

Remove two elements:
Stack elements: 5 2 4 7

Input two more elements
Stack elements: 10 -1 5 2 4 7

Minimum value: -1

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program to identify and display the minimum element in a stack implemented using an array.
• Develop a C++ program to traverse an array-based stack and find the lowest element with error-checking for empty stacks.
• Design a C++ program to implement an array-based stack and continuously update the minimum value during push operations.
• Implement a C++ program that scans an array-based stack for the smallest element and outputs it.

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Previous C++ Exercise: Find the maximum element in a stack (using an array).
Next C++ Exercise: Find the middle element of a stack (using an array).