//-----------------------------------------------------------
//  Purpose:    Check pattern using a stack
//  Author:     John Gauch
//-----------------------------------------------------------
#include "stack3/stack3.h"
#include <cstdlib> 
#include <string>
using namespace std;

//-----------------------------------------------------------
// Check that pattern is of the form aaabbb
//-----------------------------------------------------------
bool check_pattern(string str)
{
   Stack stack;

   // Read and process input string 
   for(unsigned int i=0; i < str.length(); i++)
   {
      if(str[i] == 'a')
         stack.Push('a');
      else if (str[i] == 'b')
         stack.Pop();
   }

   // Check if stack is empty
   if (stack.IsEmpty())
      return true;
   else
      return false;
}

//-----------------------------------------------------------
// Main program.
//-----------------------------------------------------------
int main()
{
   cout << "Enter pattern: ";
   string str;
   cin >> str;

   if (check_pattern(str))
      cout << "Pattern matches" << endl;
   else
      cout << "Pattern does NOT match" << endl;
   return 0;
}