50 lines
1.6 KiB
Perl
50 lines
1.6 KiB
Perl
#!/usr/bin/env perl
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use warnings;
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use strict;
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use feature 'say';
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print <<'EOF';
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The 24 Game
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Given any four digits in the range 1 to 9, which may have repetitions,
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Using just the +, -, *, and / operators; and the possible use of
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parentheses, (), show how to make an answer of 24.
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An answer of "q" or EOF will quit the game.
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A blank answer will generate a new set of four digits.
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Otherwise you are repeatedly asked for an expression until it evaluates to 24.
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Note: you cannot form multiple digit numbers from the supplied digits,
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so an answer of 12+12 when given 1, 2, 2, and 1 would not be allowed.
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EOF
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my $try = 1;
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while (1) {
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my @digits = map { 1+int(rand(9)) } 1..4;
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say "\nYour four digits: ", join(" ", @digits);
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print "Expression (try ", $try++, "): ";
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my $entry = <>;
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if (!defined $entry || substr($entry,0,1) eq 'q')
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{ say "Goodbye. Sorry you couldn't win."; last; }
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$entry =~ s/\s+//g; # remove all white space (newline is whitespace too)
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next if $entry eq '';
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my $given_digits = join "", sort @digits;
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my $entry_digits = join "", sort grep { /\d/ } split(//, $entry);
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if ($given_digits ne $entry_digits)
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{ say "incorrect digits"; next; }
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if ($entry =~ /\d\d/)
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{ say "error, combined digits"; next; }
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if ($entry =~ m|[-+*/]{2}|)
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{ say "error, combined operators"; next; }
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if ($entry =~ tr|-0-9()+*/||c)
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{ say "invalid characters!"; next; }
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my $n = eval $entry;
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if (!defined $n) { say "Invalid expression"; }
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elsif ($n == 24) { say "You win!"; last; }
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else { say "Sorry, your expression is $n, not 24"; }
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}
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