Design a dynamic stack using arrays that supports getMin() in O(1) time and O(1) extra space

// Java program for the above approach
public class Main
{
    // Initial size of
    // the Array
    static int Max = 5;
    
    // Array for the stack
    // implementation
    static int[] arr = new int[Max];
    
    // Stores the minimum
    // Element of the stack
    static int minEle = 0;
    
    // Stores the top element
    // of the stack
    static int Top = 0;
      
    // Method to check whether
    // stack is empty or not
    static boolean empty()
    {
        if (Top <= 0) {
            return true;
        }
        else {
            return false;
        }
    }
    // Method to push elements
    // to the Special Stack
    static void push(int x)
    {
        // If stack is empty
        if (empty()) {
    
            // Assign x to minEle
            minEle = x;
    
            // Assign x to arr[top]
            arr[Top] = x;
    
            // Increment top by 1
            Top++;
        }
        // If array is full
        else if (Top == Max) {
    
            // Update the Max size
            Max = 2 * Max;
    
            int[] temp = new int[Max];
    
            // Traverse the array arr[]
            for (int i = 0; i < Top; i++) {
                temp[i] = arr[i];
            }
    
            // If x is less than minEle
            if (x < minEle) {
    
                // Push 2*x-minEle
                temp[Top] = 2 * x - minEle;
    
                // Assign x to minEle
                minEle = x;
    
                Top++;
            }
            // Else
            else {
    
                // Push x to stack
                temp[Top] = x;
                Top++;
            }
            // Assign address of the
            // temp to arr
            arr = temp;
        }
        else {
            // If x is less
            // than minEle
            if (x < minEle) {
    
                // Push 2*x-minEle
                arr[Top] = 2 * x - minEle;
                Top++;
    
                // Update minEle
                minEle = x;
            }
            else {
                // Push x to the
                // stack
                arr[Top] = x;
                Top++;
            }
        }
    }
    // Method to pop the elements
    // from the stack.
    static void pop()
    {
        // If stack is empty
        if (empty()) {
            System.out.print("Underflow");
            return;
        }
        // Stores the top element
        // of the stack
        int t = arr[Top - 1];
    
        // If t is less than
        // the minEle
        if (t < minEle) {
            // Pop the minEle
            System.out.println("Popped element : " + minEle);
    
            // Update minEle
            minEle = 2 * minEle - t;
        }
        // Else
        else {
            // Pop the topmost element
            System.out.println("Popped element : " + t);
        }
        Top--;
        return;
    }
    
    // Method to find the topmost
    // element of the stack
    static int peek()
    {
        // If stack is empty
        if (empty()) {
            System.out.println("Underflow");
            return -1;
        }
    
        // Stores the top element
        // of the stack
        int t = arr[Top - 1];
    
        // If t is less than
        // the minEle
        if (t < minEle) {
            return minEle;
        }
        // Else
        else {
            return t;
        }
    }
    // Method to find the Minimum
    // element of the Special stack
    static int getMin()
    {
        // If stack is empty
        if (empty()) {
            System.out.println("Underflow");
            return -1;
        }
        // Else
        else {
            return minEle;
        }
    }
    
  // Driver code
    public static void main(String[] args) {
        push(10);
        push(4);
        push(9);
        push(6);
        push(5);
        
        System.out.println("Top Element : " + peek());
        
        System.out.println("Minimum Element : " + getMin());
        
        pop();
        pop();
        pop();
        pop();
        
        System.out.println("Top Element : " + peek());
        System.out.println("Minimum Element : " + getMin());
    }
}

// This code is contributed by rameshtravel07.