Beefy Boxes and Bandwidth Generously Provided by pair Networks
Syntactic Confectionery Delight
 
PerlMonks  

Re: Spiraling integers

by Limbic~Region (Chancellor)
on Aug 28, 2005 at 22:08 UTC ( #487293=note: print w/replies, xml ) Need Help??


in reply to Spiraling integers

Elijah,
I am sure there is a mathematical equation that would simplify this but I was spending too much time with my TI-89 Titanium trying to figure it out so...

There is an underlying pattern that can be reduced to simple enough instructions to end up with a single array of N2 elements populated iteratively. It didn't take me too long to figure it out once I flattened a couple of starting lists with their corresponding solutions

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 01 02 03 04 12 13 15 05 11 16 15 06 10 09 08 07 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 2 +4 25 01 02 03 04 05 16 17 18 19 06 15 24 25 20 07 14 23 22 21 08 13 12 11 1 +0 09
You can see the solution below:
#!/usr/bin/perl use strict; use warnings; my $n = $ARGV[0] || 5; my @spiral = gen_spiral($n); output(@spiral); sub output { my @spiral = @_; my $n = sqrt @spiral; my $cnt; for ( @spiral ) { print "\n" if $cnt++ % $n == 0; printf("%-3d ", $_); } } sub gen_spiral { my $n = shift; my ($tot, @spiral) = ($n * $n, ()); my ($index, $cnt, $l_border, $r_border, $fill_size) = (1, 1, 1, $t +ot, $n + 1); while ( $cnt <= $tot ) { ##### Moving right ##### # Step 1, decrease fill size --$fill_size; # Step 2, fill in for ( 1 .. $fill_size ) { $spiral[ $index++ ] = $cnt++; } --$index; # Step 3, skip by n's for ( 1 .. $fill_size - 1 ) { $index += $n; $spiral[$index] = $cnt++; } ##### Moving left ##### # Step 1, decrease fill size --$fill_size; # Step 2, fill in for ( 1 .. $fill_size ) { $spiral[ --$index ] = $cnt++; } # Step 4, skip by n's for ( 1 .. $fill_size - 1 ) { $index -= $n; $spiral[$index] = $cnt++; } ++$index; } shift @spiral; # Arrays are 0 based return @spiral; }

Cheers - L~R

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://487293]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others making s'mores by the fire in the courtyard of the Monastery: (5)
As of 2019-02-19 01:40 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    I use postfix dereferencing ...









    Results (101 votes). Check out past polls.

    Notices?