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

C++ Stack: Exercise-6 with Solution

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

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

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;
            return false;
        }
        // Increment top index and add element to array
        arr[++top] = x; 
        return true;
    }

    int pop() {
        if (isEmpty()) {
            cout << "Stack underflow" << endl;
            return 0;
        }
        // Return top element and decrement top index
        return arr[top--]; 
    }

    int peek() {
        if (isEmpty()) {
            cout << "Stack is empty" << endl;
            return 0;
        }
        // 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;
        return;
    }
    cout << "\nStack elements: ";
    for (int i = top; i >= 0; i--)
        cout << arr[i] << " ";
    cout << endl;
  }
  
int max() {
    if (isEmpty()) {
    // Return the minimum possible integer if the stack is empty	
        return INT_MIN; 
    }
    int maxVal = arr[0];
    for (int i = 1; i <= top; i++) {
        if (arr[i] > maxVal) {
    // Update the maximum value if we find a larger element        	
            maxVal = arr[i];
        }
    }
    // Return the maximum value
    return maxVal; 
}
};

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 max_val = stk.max(); 
    cout << "\nMaximum value: " << max_val << endl; // Display the maximum value
    cout << "\nRemove two elements:";
    stk.pop();
    stk.pop();
    stk.display(); 
    cout << "\nInput two more elements";
    stk.push(-1);
    stk.push(10);
    stk.display();
    max_val = stk.max(); 
    cout << "\nMaximum value: " << max_val << endl; // Display the maximum value
    cout << endl;
    return 0;
}

Sample Output:

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

Maximum value: 7

Remove two elements:
Stack elements: 5 2 4 7

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

Maximum value: 10

Flowchart:

CPP Code Editor:

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Previous C++ Exercise: Average value of the stack elements (using an array).
Next C++ Exercise: Find the minimum element in a stack (using an array).