032_times_minus.h

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#ifndef _INCL_032_TIMES_MINUS
#define _INCL_032_TIMES_MINUS
#include <iostream>
#include "032_perm032.h"
using namespace std;

class times_minus
{
  unsigned N;
  int *current_perm;
  int A, B, C;
  unsigned times_pos;           
  unsigned minus_pos;           
  void findABC ();
  int slice_perm (idx, idx);
public:
    times_minus (perm032 &);
   ~times_minus ();
  bool next_opr_pos ();
  bool isZero ();
  void printExpr ();            
  int getProduct ();
};


int
times_minus::getProduct ()
{
  return C;
}

void
times_minus::findABC ()
{
  A = slice_perm (0, times_pos);
  B = slice_perm (times_pos, minus_pos);
  C = slice_perm (minus_pos, N);
}

bool
times_minus::next_opr_pos ()
{
  times_pos++;
  if (times_pos == minus_pos)
    {                           // two operators directly adjacent
      minus_pos++;
      times_pos = 1;
    }

  if (minus_pos == N)
    {
      //reset
      /*      times_pos = 1;
         minus_pos = times_pos + 2;
         findABC (); */
      return 0;
    }

  findABC ();
  return 1;
}

bool times_minus::isZero ()
{
  return (A * B - C == 0);
}

times_minus::times_minus (perm032 & perm)
{
  times_pos = 1;
  minus_pos = times_pos + 2;

  N = perm.length ();

  current_perm = new digit[N];
  for (unsigned i = 0; i < N; i++)
    current_perm[i] = perm[i];

  findABC ();
}

times_minus::~times_minus ()
{
  delete[]current_perm;
}

void
times_minus::printExpr ()
{
  cout << A << " * " << B << " - " << C << " = " << (A * B - C) << endl;
}

int
times_minus::slice_perm (idx begin, idx end)
{
  int number = 0;
  for (idx i = begin; i < end; i++)
    number = number * 10 + current_perm[i];
  return number;
}

#endif