A stack is a data structure that operates on a Last-In, First-Out (LIFO) basis, meaning the last element added is the first one to be removed.

Time Complexities:

• Push (Insertion at Top): O(1)
• Pop (Deletion from Top): O(1)
• Peek (Top Element Access): O(1)

            #include<iostream>
            using namespace std;

            class MyStack{
                private:
                    int* array;
                    int size;
                    int capacity;
                public:
                    MyStack(){
                        array = new int[1];
                        size = 0;
                        capacity = 1;
                    }
                    int getSize(){
                        return size;
                    }
                    int getCapacity(){
                        return capacity;
                    }
                    void push(int element){
                        if(size+1>capacity){
                            int new_capacity = capacity*2;
                            int* newArray = new int[new_capacity];
                            for(int i = 0; i<size; i++){
                                newArray[i] = array[i];
                            }
                            newArray[size] = element;
                            size++;
                            array = newArray;
                            capacity = new_capacity;
                        } else {
                            array[size] = element;
                            size++;
                        }
                    }
                    void pop(){
                        size = max(size-1,0);
                    }
                    int top(){
                        if(size>0){
                            return array[size-1];
                        }
                        return -1;
                    }
                    void display(){
                        for(int i = 0; i<size; i++){
                            cout << array[i] << " ";
                        }
                    }
            };