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24 game/Solve: Difference between revisions
added perl implementation
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*<code>Permutations[Array[v, n]]</code> returns <math>n!</math> permutations.
Therefore, the size of the working set is <math>64 \cdot n!\, C_{n-1} = 64 \cdot (n-1)!!!! = 64 \frac{(2n-2)!}{(n-1)!}</math>, where <math>n!!!!</math> is the [[wp:quadruple factorial|quadruple factorial]]. It goes without saying that this number increases very fast. For this game, the total is 7680 elements. For higher numbers of inputs, it is {7 680, 107 520, 1 935 360, 42 577 920, 1 107 025 920, ...}.
=={{header|Perl}}==
Will generate all possible solutions of any given four numbers according to the rules of the [[24 game]].
Note: the <code>permute</code> function was taken from [http://faq.perl.org/perlfaq4.html#How_do_I_permute_N_e here]
<lang Perl># Fischer-Krause ordered permutation generator
# http://faq.perl.org/perlfaq4.html#How_do_I_permute_N_e
sub permute (&@) {
my $code = shift;
my @idx = 0..$#_;
while ( $code->(@_[@idx]) ) {
my $p = $#idx;
--$p while $idx[$p-1] > $idx[$p];
my $q = $p or return;
push @idx, reverse splice @idx, $p;
++$q while $idx[$p-1] > $idx[$q];
@idx[$p-1,$q]=@idx[$q,$p-1];
}
}
@formats = (
'((%d %s %d) %s %d) %s %d',
'(%d %s (%d %s %d)) %s %d',
'(%d %s %d) %s (%d %s %d)',
'%d %s ((%d %s %d) %s %d)',
'%d %s (%d %s (%d %s %d))',
);
# generate all possible combinations of operators
@op = qw( + - * / );
@operators = map{ $a=$_; map{ $b=$_; map{ "$a $b $_" }@op }@op }@op;
while(1)
{
print "Enter four integers or 'q' to exit: ";
chomp($ent = <>);
last if $ent eq 'q';
if($ent !~ m/^[1-9] [1-9] [1-9] [1-9]$/){ print "invalid input\n"; next }
@n = split / /,$ent;
permute { push @numbers,join ' ',@_ }@n;
for(@formats)
{
$format = $_;
for(@numbers)
{
@n = split;
for(@operators)
{
@o = split;
$str = sprintf $format,$n[0],$o[0],$n[1],$o[1],$n[2],$o[2],$n[3];
$r = eval($str);
print "$str\n" if $r == 24;
}
}
}
}</lang>
=={{header|Python}}==
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