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Think about Loose Coupling
 
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You can still generate the full array of counts afterwards and have a speed benefit, because you only have to iterate once over the big array (as opposed to once per overlap in your current implementation).

Update:

Example code for obtaining the full array:

use strict; use warnings; my @a = (10, 15, -20, -30); my $highest = abs($a[-1]); my @full = (0) x ($highest + 1); # decrement all negative values by 1, otherwise # we would exclude the end points: for (@a) { $_-- if $_ < 0; } my $count = 0; for (0..$highest) { if (abs $a[0] == $_) { my $c = shift @a; if ($c > 0) { $count++; } else { $count--; } } $full[$_] += $count; } print join('', @full), "\n";

This assumes that there are never two values of same magnitude in the array, ie never exactly matching start- and endpoints. You can generalize it on your own :-)

Second update: I've just realized that the extension is very simple:

Instead of if (abs $a[0] == $_) write while (abs $a[0] == $_), and you're done.


In reply to Re^3: Optimizing a double loop by moritz
in thread Optimizing a double loop by roibrodo

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