diff options
| -rw-r--r-- | challenge-102/james-smith/perl/ch-1.pl | 66 |
1 files changed, 62 insertions, 4 deletions
diff --git a/challenge-102/james-smith/perl/ch-1.pl b/challenge-102/james-smith/perl/ch-1.pl index 930d91cc65..8365cdbafc 100644 --- a/challenge-102/james-smith/perl/ch-1.pl +++ b/challenge-102/james-smith/perl/ch-1.pl @@ -3,14 +3,72 @@ use strict; use warnings; -use feature qw(say); +use feature qw(say state); use Test::More; -is( my_function(), 1 ); +my @rare_ends = ( [2,[2]], [4,[0]], [6,[0,5]], [8,[2,3,7,8]] ); + +is( "@{[ rare_numbers( 2 ) ]}", '65' ); +is( "@{[ rare_numbers( 6 ) ]}", '621770' ); +is( "@{[ rare_numbers( 9 ) ]}", '281089082' ); +is( "@{[ rare_numbers( 10 ) ]}", "2022652202 2042832002" ); done_testing(); -sub my_function { - return 1; + sub is_sq { + state %cache; + return $cache{$_[0]} if exists $cache{$_[0]}; + return $cache{$_[0]} = ( $_[0] =~ m{[014569]$} && $_[0] == (int sqrt $_[0])**2 ); + } + +sub rare_numbers { + my $size = shift; + my @F=(0,1,0,1,1,0,1,1,0); ## rare_numbers have a digit sum (value mod 9) of either 9/0,2,5 or 8 + sub is_rare { + my $x = shift; + return () if $F[$x%9]; ## Digit sum is wrong... + my $y = reverse $x; + return () if $x == $y; ## Musn't be the same back and forth + return $y if $x<$y && is_sq($x+$y) && is_sq($y-$x); ## Check both ways round! + return $x if $y<$x && is_sq($x+$y) && is_sq($x-$y); + return (); + } + + my %res; + my $low = $size <= 4 ? '' : '0' x ($size-4); + my $high = $size <= 4 ? '' : '9' x ($size-4); + + foreach my $tup ( @rare_ends ) { + my $s = $tup->[0]; ## first digit has to be even 2,4,6,8 + foreach my $e (@{$tup->[1]}) { ## second digit has to be in list at start... + if( $size == 2 ) { ## As our method really starts at 4 let us deal with 2 & 3 cases first... + $res{$_}=1 foreach is_rare("$s$e"); + next; + } + if( $size == 3 ) { + $res{$_}=1 foreach map { is_rare("$s$_$e") } 0..9; + next; + } + + ## Now we need to do the next group.... + foreach my $b (0..9) {## These are filters to apply for each group of numbers.... + foreach my $f (0..9) { + next if $s==2 && $b!=$f + || $s==4 && ($b-$f)%2 + || $s==6 && ! ($b-$f)%2 + || $s==8 && ( + $e==2 && $b+$f!=9 + || $e==3 && $b-$f!=7 && $f-$b !=3 + || $e==7 && $b+$f!=1 && $b+$f !=11 + || $e==8 && $b!=$f + ); + ## Now we try all additional numbers.... + ## The sequence '000' .. '999' gives all 3 digit numbers.... ! + $res{$_}=1 foreach map { is_rare("$s$b$_$f$e") } $low..$high; + } + } + } + } + return sort keys %res; } |