MinStack.txt

import java.util.Stack;

public class MinStack {
    private Stack<Integer> stack; // Main stack to store elements
    private Stack<Integer> minStack; // Auxiliary stack to store minimum values

    public MinStack() {
        stack = new Stack<>();
        minStack = new Stack<>();
    }

    // Push operation: Pushes an element onto the stack
    public void push(int val) {
        stack.push(val);

        // Check if the minStack is empty or if the new element is the minimum
        if (minStack.isEmpty() || val <= minStack.peek()) {
            minStack.push(val);
        }
    }

    // Pop operation: Removes the element at the top of the stack
    public void pop() {
        if (!stack.isEmpty()) {
            // If the element to be removed is the minimum, update minStack
            if (stack.peek().equals(minStack.peek())) {
                minStack.pop();
            }
            stack.pop();
        }
    }

    // Top operation: Retrieves the element at the top of the stack
    public int top() {
        return stack.peek();
    }

    // Get Minimum operation: Retrieves the minimum element in the stack
    public int getMin() {
        return minStack.peek();
    }

    public static void main(String[] args) {
        MinStack minStack = new MinStack();
        minStack.push(-2);
        minStack.push(0);
        minStack.push(-3);

        System.out.println("Minimum element: " + minStack.getMin());
        minStack.pop();
        System.out.println("Top element: " + minStack.top());
        System.out.println("Minimum element after pop: " + minStack.getMin());
    }
}