# include <cstdlib>
# include <iostream>
# include <iomanip>
# include <ctime>
# include <cmath>

using namespace std;

int main ( int argc, char *argv[] );
int i4_div_rounded ( int a, int b );
int i4_huge ( void );
int i4_sign ( int i );
void task_divide ( int task_number, int proc_first, int proc_last );
void timestamp ( void );

//****************************************************************************80

int main ( int argc, char *argv[] )

//****************************************************************************80
//
//  Purpose:
//
//    MAIN is the main program for TASK_DIVISION.
//
//  Discussion:
//
//    This program simply demonstrates how one might automate the
//    assignment of T tasks to P processors, assuming that the assignment
//    is to be beforehand.
//
//    In that case, we just want to make sure that we assign each task
//    to a processor, that we assign about the same number of tasks
//    to each processor, and that we assign each processor a contiguous
//    range of tasks, say tasks I_LO to I_HI.
//
//    The routine that is called simulates this process.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license. 
//
//  Modified:
//
//    21 October 2007
//
//  Author:
//
//    John Burkardt
//
{
  int proc_first;
  int proc_last;
  int task_number;

  timestamp ( );

  cout << "\n";
  cout << "TASK_DIVISION:\n";
  cout << "  C++ version\n";
  cout << "\n";
  cout << "  Demonstrate how to automate the assignment of\n";
  cout << "  T tasks among P processors.\n";

  task_number = 23;
  proc_first = 0;
  proc_last = 3;
  task_divide ( task_number, proc_first, proc_last );

  task_number = 17;
  proc_first = 1;
  proc_last = 6;
  task_divide ( task_number, proc_first, proc_last );

  task_number = 17;
  proc_first = 4;
  proc_last = 6;
  task_divide ( task_number, proc_first, proc_last );

  task_number = 5;
  proc_first = -2;
  proc_last = 6;
  task_divide ( task_number, proc_first, proc_last );

  task_number = 5;
  proc_first = 0;
  proc_last = 4;
  task_divide ( task_number, proc_first, proc_last );

  task_number = 5;
  proc_first = 0;
  proc_last = 0;
  task_divide ( task_number, proc_first, proc_last );

  task_number = 1000;
  proc_first = 1;
  proc_last = 17;

  task_divide ( task_number, proc_first, proc_last );

  cout << "\n";
  cout << "TASK_DIVISION:\n";
  cout << "  Normal end of execution.\n";

  cout << "\n";
  timestamp ( );

  return 0;
}
//****************************************************************************80

int i4_div_rounded ( int a, int b )

//****************************************************************************80
//
//  Purpose:
//
//    I4_DIV_ROUNDED computes the rounded result of I4 division.
//
//  Discussion:
//
//    This routine computes C = A / B, where A, B and C are integers
//    and C is the closest integer value to the exact real result.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license. 
//
//  Modified:
//
//    21 October 2007
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    Input, int A, B, the number to be divided,
//    and the divisor.
//
//    Output, int I4_DIV_ROUNDED, the rounded result
//    of the division.
//
{
  int a_abs;
  int b_abs;
  int c;
  int c_abs;
  int c_s;

  if ( a == 0 )
  {
    c_abs = i4_huge ( );
    c_s = i4_sign ( b );
  }
  else
  {
    a_abs = abs ( a );
    b_abs = abs ( b );
    c_s = i4_sign ( a ) * i4_sign ( b );

    c_abs = a_abs / b_abs;

    if ( ( 2 * c_abs + 1 ) * b_abs < 2 * a_abs )
    {
      c_abs = c_abs + 1;
    }
  }

  c = c_s * c_abs;

  return c;
}
//****************************************************************************80

int i4_huge ( void )

//****************************************************************************80
//
//  Purpose:
//
//    I4_HUGE returns a "huge" I4.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license. 
//
//  Modified:
//
//    16 May 2003
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    Output, int I4_HUGE, a "huge" I4.
//
{
  return 2147483647;
}
//****************************************************************************80

int i4_sign ( int i )

//****************************************************************************80
//
//  Purpose:
//
//    I4_SIGN returns the sign of an I4.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license. 
//
//  Modified:
//
//    27 March 2004
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    Input, int I, the integer whose sign is desired.
//
//    Output, int I4_SIGN, the sign of I.
{
  int value;

  if ( i < 0 ) 
  {
    value = -1;
  }
  else
  {
    value = 1;
  }
  return value;
}
//****************************************************************************80

void task_divide ( int task_number, int proc_first, int proc_last )

//****************************************************************************80
//
//  Purpose:
//
//    TASK_DIVIDE divides tasks among processors.
//
//  Discussion:
//
//    This routine assigns each of T tasks to P processors, assuming that 
//    the assignment is to be beforehand.
//
//    In that case, we just want to make sure that we assign each task
//    to a processor, that we assign about the same number of tasks
//    to each processor, and that we assign each processor a contiguous
//    range of tasks, say tasks I_LO to I_HI.
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license. 
//
//  Modified:
//
//    20 October 2007
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    Input, int TASK_NUMBER, the number of tasks.
//
//    Input, int PROC_FIRST, PROC_LAST, the first and last processors.
//
{
  int i_hi;
  int i_lo;
  int proc;
  int proc_number;
  int proc_remain;
  int task_proc;
  int task_remain;

  proc_number = proc_last + 1 - proc_first;

  cout << "\n";
  cout << "TASK_DIVIDE\n";
  cout << "  Divide T tasks among P processors.\n";
  cout << "\n";
  cout << "  P(first) = " << proc_first << "\n";
  cout << "  P(last) =  " << proc_last << "\n";
  cout << "\n";
  cout << "  T = " << task_number << "\n";
  cout << "  P = " << proc_number << "\n";

  cout << "\n";
  cout << " Processor     Tasks     First      Last\n";
  cout << "\n";

  i_hi = 0;

  task_remain = task_number;
  proc_remain = proc_number;

  for ( proc = proc_first; proc <= proc_last; proc++ )
  {
    task_proc = i4_div_rounded ( task_remain, proc_remain );

    proc_remain = proc_remain - 1;
    task_remain = task_remain - task_proc;

    i_lo = i_hi + 1;
    i_hi = i_hi + task_proc;

    cout << "  " << setw(8) << proc
         << "  " << setw(8) << task_proc
         << "  " << setw(8) << i_lo
         << "  " << setw(8) << i_hi << "\n";
  }

  return;
}
//****************************************************************************80

void timestamp ( void )

//****************************************************************************80
//
//  Purpose:
//
//    TIMESTAMP prints the current YMDHMS date as a time stamp.
//
//  Example:
//
//    May 31 2001 09:45:54 AM
//
//  Licensing:
//
//    This code is distributed under the GNU LGPL license. 
//
//  Modified:
//
//    03 October 2003
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    None
//
{
# define TIME_SIZE 40

  static char time_buffer[TIME_SIZE];
  const struct tm *tm;
  size_t len;
  time_t now;

  now = time ( NULL );
  tm = localtime ( &now );

  len = strftime ( time_buffer, TIME_SIZE, "%d %B %Y %I:%M:%S %p", tm );

  cout << time_buffer << "\n";

  return;
# undef TIME_SIZE
}