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| -rw-r--r-- | challenge-048/luca-ferrari/raku/ch-1.p6 | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/challenge-048/luca-ferrari/raku/ch-1.p6 b/challenge-048/luca-ferrari/raku/ch-1.p6 new file mode 100644 index 0000000000..f8f29f1f71 --- /dev/null +++ b/challenge-048/luca-ferrari/raku/ch-1.p6 @@ -0,0 +1,57 @@ +#!env raku + +# Perl Weekly Challenge 48 +# see <https://perlweeklychallenge.org/blog/perl-weekly-challenge-048/> +# +# Task 1 +# Survivor +# +# There are 50 people standing in a circle in position 1 to 50. +# The person standing at position 1 has a sword. +# He kills the next person i.e. standing at position 2 and pass on the +# sword to the immediate next i.e. person standing at position 3. +# Now the person at position 3 does the same and it goes on until only one survives. +# +# Write a script to find out the survivor. + + +# Given the list of people, find out +# the next living person after the current one specified. +# +# Implements the list rotation. +sub next-alive( @people, $current-person ) { + my $next = $current-person; + + loop { + $next++; + $next = $next >= @people.elems ?? $next % @people.elems !! $next; + return $next if @people[ $next ].defined; + } +} + + + +sub MAIN( Int :$how_many_people = 50 ) { + + # False means that the person does not have the sword, + # True means she has + # Nil means the person is died + my @people = False xx $how_many_people; + + # give the sword + @people[ 0 ] = True; + + while ( @people.grep( *.defined ) > 1 ) { + # find out who has the sword + my $killer = @people.first: *.so, :k; + # then find out the next person to kill + my $killed = next-alive( @people, $killer ); + @people[ $killed ] = Nil; # killed! + @people[ $killer ] = False; # pass the sword + # now get the next person that will hold the sword + my $next-killer = next-alive( @people, $killed ); + @people[ $next-killer ] = True; # the next killer + } + + "The person who survives is { $_ + 1 }".say given @people.first: *.so, :k; +} |