#! perl -slw
use strict;
use Data::Dumper;
use List::Util qw[ reduce first ];

our $N ||= 100;
our $MIN ||= 10;

my @data = sort{ $a->[ 0 ] <=> $b->[ 0 ] } map{ [ rand 1000, int rand 10 ] } 1 .. $N;
print Dumper \@data;

my @intervals;
reduce {
    push @intervals, [ abs( $data[ $a ][ 0 ] - $data[ $b ][ 0 ] ), $a, $b ];
    $b;
} 0 .. $#data;

@intervals = sort { $a->[0] <=> $b->[0] } @intervals;

while( grep( defined, @data ) > $MIN ) {
    my( $i, $x, $y ) = @{ shift @intervals };
    next unless defined $data[ $x ] and defined $data[ $y ];
    my $discard = $data[ $x ][ 1] < $data[ $y ][ 1 ] ? $x : $y;
    delete $data[ $discard ];
    if( $discard == $x ) {
        --$x while $x > 0 and not defined $data[ $x ];
        next if $x == 0 or not defined $data[ $x ];
    }
    else {
        ++$y while $y < $#data and not defined $data[ $y ];
        next if $y == $#data or not defined $data[ $y ];
    }
    my $newInterval = [ abs( $data[ $x ] - $data[ $y ] ), $x, $y ];
    my $insertPoint = first{ $intervals[ $_ ][0] > $newInterval->[0] } 0 .. $#intervals;
    $insertPoint = $#intervals unless defined $insertPoint;
    splice @intervals, $insertPoint, 0, $newInterval;
}

@data = grep defined, @data;
print Dumper \@data;

__END__
$VAR1 = [
          [ '10.101318359375', 0 ],
          [ '15.472412109375', 8 ],
*          [ '21.209716796875', 9 ],
          [ '41.80908203125', 1 ],
          [ '45.379638671875', 0 ],
*          [ '72.6318359375', 7 ],
          [ '80.047607421875', 1 ],
          [ '89.019775390625', 0 ],
*          [ '94.90966796875', 8 ],
          [ '101.470947265625', 6 ],
          [ '133.36181640625', 5 ],
          [ '142.913818359375', 6 ],
          [ '151.2451171875', 6 ],
          [ '168.15185546875', 2 ],
          [ '169.403076171875', 7 ],
          [ '174.01123046875', 5 ],
          [ '182.037353515625', 8 ],
          [ '185.9130859375', 7 ],
          [ '223.57177734375', 1 ],
          [ '231.99462890625', 7 ],
          [ '236.02294921875', 5 ],
          [ '262.359619140625', 3 ],
          [ '263.031005859375', 7 ],
          [ '279.1748046875', 1 ],
          [ '280.303955078125', 0 ],
          [ '289.73388671875', 8 ],
          [ '308.41064453125', 3 ],
          [ '317.657470703125', 1 ],
          [ '324.5849609375', 6 ],
*          [ '341.033935546875', 9 ],
          [ '343.170166015625', 0 ],
          [ '353.271484375', 3 ],
          [ '355.438232421875', 6 ],
          [ '371.27685546875', 3 ],
          [ '379.241943359375', 3 ],
          [ '382.62939453125', 0 ],
*          [ '386.23046875', 9 ],
          [ '389.34326171875', 3 ],
          [ '394.47021484375', 0 ],
          [ '399.4140625', 1 ],
          [ '407.440185546875', 2 ],
          [ '425.201416015625', 6 ],
          [ '426.361083984375', 0 ],
          [ '438.65966796875', 3 ],
          [ '447.93701171875', 5 ],
          [ '455.810546875', 7 ],
          [ '457.45849609375', 1 ],
          [ '465.51513671875', 5 ],
          [ '468.8720703125', 6 ],
          [ '475.799560546875', 4 ],
          [ '491.14990234375', 5 ],
          [ '496.2158203125', 9 ],
          [ '503.570556640625', 7 ],
          [ '511.566162109375', 2 ],
          [ '543.3349609375', 9 ],
          [ '561.767578125', 6 ],
          [ '563.690185546875', 0 ],
          [ '571.8994140625', 2 ],
          [ '574.89013671875', 3 ],
          [ '595.21484375', 7 ],
          [ '600.03662109375', 3 ],
          [ '608.062744140625', 1 ],
          [ '615.081787109375', 8 ],
          [ '631.195068359375', 9 ],
          [ '634.33837890625', 2 ],
          [ '638.031005859375', 5 ],
          [ '639.251708984375', 7 ],
          [ '672.30224609375', 8 ],
          [ '672.698974609375', 5 ],
          [ '678.64990234375', 3 ],
          [ '690.73486328125', 7 ],
          [ '710.63232421875', 5 ],
          [ '718.475341796875', 4 ],
          [ '761.3525390625', 2 ],
          [ '770.69091796875', 9 ],
          [ '790.6494140625', 1 ],
*          [ '796.417236328125', 8 ],
          [ '807.647705078125', 4 ],
          [ '809.38720703125', 1 ],
          [ '809.9365234375', 3 ],
*          [ '813.873291015625', 5 ],
          [ '819.76318359375', 4 ],
          [ '821.6552734375', 4 ],
          [ '833.80126953125', 5 ],
*          [ '843.170166015625', 8 ],
          [ '843.505859375', 2 ],
          [ '861.99951171875', 4 ],
          [ '865.6005859375', 5 ],
          [ '866.14990234375', 6 ],
          [ '871.124267578125', 4 ],
*          [ '890.960693359375', 9 ],
          [ '911.102294921875', 1 ],
          [ '912.353515625', 7 ],
          [ '919.708251953125', 1 ],
          [ '922.91259765625', 8 ],
          [ '956.695556640625', 2 ],
          [ '973.388671875', 5 ],
*          [ '977.142333984375', 8 ],
          [ '993.438720703125', 8 ],
          [ '998.1689453125', 5 ]
        ];

$VAR1 = [
          [ '21.209716796875', 9 ],
          [ '72.6318359375', 7 ],
          [ '94.90966796875', 8 ],
          [ '341.033935546875', 9 ],
          [ '386.23046875', 9 ],
          [ '796.417236328125', 8 ],
          [ '813.873291015625', 5 ],
          [ '843.170166015625', 8 ],
          [ '890.960693359375', 9 ],
          [ '977.142333984375', 8 ]
        ];