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#!/usr/bin/env raku
use v6.d;
# Second attempt at this using a different plan
#| Given a list of integers return all the wave sorted lists
multi sub MAIN( *@input where { $_.elems >= 2 && $_.all ~~ Int } ) {
.say for find-waves( [], @input ).race.map( { $_.join(",") } );
}
# Start state
multi sub find-waves( [], @input is copy ) {
gather {
for @input.kv -> $i, $val {
my @poss = @input[0..^$i,$i^..*-1].flat;
take $_ for find-waves( [$val], @poss, 'gte' ).grep( { defined $_ } );
}
}
}
# End state
multi sub find-waves( @i, [] where { True }, 'gte' ) { ( @i, ); }
multi sub find-waves( @i, [] where { True }, 'lte' ) { ( @i, ); }
# Fail States
multi sub find-waves( @i, @p where { @i[*-1] < all(@p) }, 'gte' ) {}
multi sub find-waves( @i, @p where { @i[*-1] > all(@p) }, 'lte' ) {}
# Possible State
multi sub find-waves( @output is copy, @input is copy, $test ) {
gather {
my &test = $test ~~ 'gte' ?? &infix:«>=» !! &infix:«<=»;
for @input.kv -> $i, $val {
next unless &test( @output[*-1], $val );
my @poss = @input[0..^$i,$i^..*-1].flat;
take $_ for find-waves( [|@output, $val], @poss, $test ~~ 'gte' ?? 'lte' !! 'gte' ).grep( { defined $_ } );
}
}
}
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