Question

write an implementation of the ADT stack that uses a resizeable array to represent the stack items. Anytime the stack becomes full, double the size of the array. Maintain the stack's top entry at the end of the array. Please use c++ for this question.

Answer 1

#include<iostream> #include<stdlib.h>    using namespace std;    /* A simple stack class with basic stack funtionalities */ class Stack { private:     static const int max = 100;     int arr[max];     int top; public:     Stack() { top = -1; }     bool isEmpty();     bool isFull();     int pop();     void push(int x); };    /* Stack's member method to check if the stack is iempty */ bool Stack::isEmpty() {     if(top == -1)         return true;     return false; }    /* Stack's member method to check if the stack is full */ bool Stack::isFull() {     if(top == max - 1)         return true;     return false; }    /* Stack's member method to remove an element from it */ int Stack::pop() {     if(isEmpty())     {         cout<<"Stack Underflow";         abort();     }     int x = arr[top];     top--;     return x; }    /* Stack's member method to insert an element to it */ void Stack::push(int x) {     if(isFull())     {         cout<<"Stack Overflow";         abort();     }     top++;     arr[top] = x; }    /* A class that supports all the stack operations and one additional   operation getMin() that returns the minimum element from stack at   any time. This class inherits from the stack class and uses an   auxiliarry stack that holds minimum elements */ class SpecialStack: public Stack {     Stack min; public:     int pop();     void push(int x);     int getMin(); };    /* SpecialStack's member method to insert an element to it. This method    makes sure that the min stack is also updated with appropriate minimum    values */ void SpecialStack::push(int x) {     if(isEmpty()==true)     {         Stack::push(x);         min.push(x);     }     else     {         Stack::push(x);         int y = min.pop();         min.push(y);         if( x < y )           min.push(x);         else           min.push(y);     } }    /* SpecialStack's member method to remove an element from it. This method    removes top element from min stack also. */ int SpecialStack::pop() {     int x = Stack::pop();     min.pop();     return x; }    /* SpecialStack's member method to get minimum element from it. */ int SpecialStack::getMin() {     int x = min.pop();     min.push(x);     return x; }    /* Driver program to test SpecialStack methods */ int main() {     SpecialStack s;     s.push(10);     s.push(20);     s.push(30);     cout<<s.getMin()<<endl;     s.push(5);     cout<<s.getMin();     return 0; }

Output:
10
5