I tried this to emulate a sparse array

#!/usr/bin/perl

use strict;
use warnings;

my %sparse;
@sparse{1,1,1,0,0,1,1,0,2,1,1,1,1,1} = ();
print "There are ", scalar keys %sparse, " elements in this array\n";
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Since we know that the elements are 0, 1, and 2, the output should be 3 elements.