#!/usr/bin/env perl
# Copyright 2005 Daniel Cer (daniel.cer@cs.colorado.edu)
#
# This work is licensed under the Creative Commons Attribution-NonCommercial-
# ShareAlike License. To view a copy of this license, visit 
# http://creativecommons.org/licenses/by-nc-sa/2.5/ or send a letter to 
# Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 
# 94105, USA.

sub selection_sort($) {
  my $entries_ref = shift;
  my ($i, $j, $min_idx, $N_entries_ref, $tmp_swap);
  for ($i = 0; $i <= $#{$entries_ref}; $i++) {
    # find minimum value in the range i..(Number_of_entries-1) 
    for ($j = $i+1, $min_idx = $i; $j <= $#{$entries_ref}; $j++) {
      $min_idx = $j if ($$entries_ref[$j] < $$entries_ref[$min_idx]); 
    }
    # if needed, swap the $i-th entry with the $min_idx entry 
    next if ($min_idx == $i);
    ($$entries_ref[$i],$$entries_ref[$min_idx]) =
      ($$entries_ref[$min_idx],$$entries_ref[$i]);
  }
}

if ($#ARGV != 0) {
  print stderr "Usage:\n\t$0 (file with numbers to sort)\n";
  exit -1;
}

# read in entries
$file_name = $ARGV[0];
open fh, $file_name or die "Can't open \"$file_name\"\n";
@entries = <fh>;
close fh;

# sort them
selection_sort(\@entries);

# display the results
for ($i = 0; $i <= $#entries; $i++) { print "$entries[$i]"; }