#!/usr/bin/perl -w
use strict;
use CGI qw(:standard);
print header;
print start_html('The RUNG Answer'),
h1('Random *Unique Number Generator'),
"Random numbers will be unique within each set.  ",
"Each row of output represents one set.  ",
    start_form,
    "How many numbers per set? ",textfield(-name=>'cnt',
                                           -size=>3,
                                           -maxlength=>3),
    p,
    "How many sets? ",textfield(-name=>'sets',
                                -size=>3,
                                -maxlength=>3),
    p,
    "Lowest number ? ",textfield(-name=>'low_end',
                                 -size=>5,
                                 -maxlength=>5),
    p,
    "Highest number ? ",textfield(-name=>'high_end',
                                  -size=>5,
                                  -maxlength=>5),
    p,
    submit(-name=>'Submit')," ",defaults(-name=>'Reset'),
    end_form,
    hr;

if (param) {
my $start;
my @random_numbers;
my $low_end = int(param('low_end'));
my $high_end = int(param('high_end'));
my $cnt = int(param('cnt'));
my $sets = int(param('sets'));
my $set;
my $done;

if ($cnt > 100) {
   CntErrorMessage();
   exit 1;
}

if ($sets > 100) {
   SetsErrorMessage();
   exit 1;
}

if ($low_end >= $high_end) {
   LowHighErrorMessage();
   exit 1;
}

if ($cnt > ($high_end - $low_end + 1)) {
   OverloadErrorMessage();
   exit 1;
}

for (1..$sets){
   $start = 1;
   $done = 0;
   do{ 
      GetUniqueRandomNumbers();
   } until $done;

   @random_numbers = sort by_number @random_numbers;   
   $set = join(" : ", @random_numbers);
   print "<P>$set</P>"; 
   @random_numbers = ();
}  

print end_html;
 
#subroutines

sub GetUniqueRandomNumbers{
   my $unique = 0;
   my $current_number = GetRandomNumber();
   if ($start) {
      push(@random_numbers,$current_number);  
      $start = 0;
   } else {
      foreach (@random_numbers){
         if ($_ != $current_number){ 
            $unique++;
         }
      }
      if ($unique == scalar(@random_numbers)){
         push(@random_numbers,$current_number);  
      } 
   }
   if (scalar(@random_numbers) == $cnt){
      $done = 1;
   } 
}

sub GetRandomNumber{
  my $random_number = rand($high_end - $low_end) + $low_end;
  return sprintf("%.0f", $random_number);
}

sub by_number{
   if ($a < $b){
      return -1;
   } elsif ($a == $b) {
      return 0;
   } elsif ($a > $b) {
      return 1;
   }
}

sub CntErrorMessage{
   print "There is a limit of 100 random numbers per set.";
   print end_html;
}

sub SetsErrorMessage{
   print "There is a limit of 100 sets of random numbers.";
   print end_html;
}

sub OverloadErrorMessage{
   print "I cannot give you unique numbers in this case, decrease the amount of numbers you want or increase your range.";
   print end_html;
}

sub LowHighErrorMessage{
   print "Check your range.  Your low end number should be lower than the high end number.";
   print end_html;
}

}