# include <stdlib.h>
# include <stdio.h>
# include <time.h>

int main ( );
int search ( int a, int b, int c );
int f ( int i );

/******************************************************************************/

int main ( )

/******************************************************************************/
/*
  Purpose:

    MAIN is the main program for SEARCH.

  Licensing:

    This code is distributed under the GNU LGPL license.

  Modified:

    22 October 2012

  Author:

    John Burkardt
*/
{
  int a;
  int b;
  int c;
  int fj;
  int i4_huge = 2147483647;
  int j;
  double wtime = 0.0;

  a = 1;
  b = i4_huge;
  c = 45;

  printf ( "\n" );
  printf ( "SEARCH:\n" );
  printf ( "  C version\n" );
  printf ( "  Search the integers from A to B\n" );
  printf ( "  for a value J such that F(J) = C.\n" );
  printf ( "\n" );
  printf ( "  A           = %d\n", a );
  printf ( "  B           = %d\n", b );
  printf ( "  C           = %d\n", c );

/* wtime = ?; */

  j = search ( a, b, c );

/* wtime = ? - wtime */;

  if ( j == -1 )
  {
    printf ( "\n" );
    printf ( "  No solution was found.\n" );
  }
  else
  {
    printf ( "\n" );
    printf ( "  Found     J = %d\n", j );
    printf ( "  Verify F(J) = %d\n", f ( j ) );
  }

  printf ( "  Elapsed CPU time is %g\n", wtime );
/*
  Terminate.
*/
  printf ( "\n" );
  printf ( "SEARCH:\n" );
  printf ( "  Normal end of execution.\n" );

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

int search ( int a, int b, int c )

/******************************************************************************/
/*
  Purpose:

    SEARCH searches integers in [A,B] for a J so that F(J) = C.

  Licensing:

    This code is distributed under the GNU LGPL license.

  Modified:

    22 October 2012

  Author:

    John Burkardt

  Parameters:

    Input, int A, B, the search range.

    Input, int C, the desired function value.

    Output, int SEARCH, the computed solution, or -1
    if no solution was found.
*/
{
  int fi;
  int i;
  int j;

  j = -1;

  for ( i = a; i <= b; i++ )
  {
    fi = f ( i );

    if ( fi == c )
    {
      j = i;
      break;
    }
  }

  return j;
}
/******************************************************************************/

int f ( int i )

/******************************************************************************/
/*
  Purpose:

    F is the function we are analyzing.

  Licensing:

    This code is distributed under the GNU LGPL license.

  Modified:

    22 October 2012

  Author:

    John Burkardt

  Parameters:

    Input, int I, the argument.

    Input, int F, the value.
*/
{
  int i4_huge = 2147483647;
  int j;
  int k;
  int value;

  value = i;

  for ( j = 1; j <= 5; j++ )
  {
    k = value / 127773;

    value = 16807 * ( value - k * 127773 ) - k * 2836;

    if ( value <= 0 )
    {
      value = value + i4_huge;
    }
  }

  return value;
}