Task 1 done.

1 files changed, 81 insertions, 0 deletions

diff --git a/challenge-075/luca-ferrari/raku/ch-1.p6 b/challenge-075/luca-ferrari/raku/ch-1.p6
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+#!raku
+
+sub find-solutions( Int :$sum, :@coins ) {
+    my @solutions;
+
+    # add all the 'one coin' solutions
+    @solutions.push: [ $_ xx ( $sum / $_ ) ] for @coins.grep( $sum %% * );
+
+
+    # now inspect all the other cases
+    for @coins.grep(  $sum !%% * ).sort( { $^b <=> $^a } ) -> $current-coin {
+        next if $current-coin > $sum;
+        my @current-solution;
+        @current-solution.push: $current-coin;
+
+        for @coins.grep( * !~~ $current-coin ).sort( { $^b <=> $^a } ) {
+            my $current-sum = [+] @current-solution;
+            # try to add the same number over and over again
+            while ( ( $current-sum + $_ ) <= $sum ) {
+                @current-solution.push: $_ ;
+                $current-sum = [+] @current-solution;
+            }
+
+            if ( $current-sum == $sum  ) {
+                # use a new array to clone it, so I can delete the last value and continue over
+                @solutions.push: Array.new: @current-solution.sort;
+                @current-solution[ *-1 ]:delete;
+                next;
+            }
+        }
+
+    }
+
+
+    # last step: decompose every number in a solution into other numbers
+    my @decomposed-solutions;
+    for @solutions -> @current-solution {
+        for 0 ..^ @current-solution.elems -> $switching-index {
+
+            my $current-coin = @current-solution[ $switching-index ];
+            next if $current-coin ~~ 1;
+
+            for @coins.grep( $current-coin %% * ) {
+                next if $_ ~~ $current-coin;
+                my @new-solution = Array.new: @current-solution;
+                @new-solution[ $switching-index ]:delete;
+                @new-solution[ $switching-index ] = | ( $_ xx ( $current-coin / $_ ) );
+                @decomposed-solutions.push: [ @new-solution.sort ];
+            }
+        }
+    }
+
+
+    # now build something unique
+    my %unique-solutions;
+    for @decomposed-solutions {
+        %unique-solutions{ "{ $_ }" } = $_;
+    }
+
+    for @solutions {
+        %unique-solutions{ "{ $_ }" } = $_;
+    }
+
+
+    %unique-solutions.values;
+}
+
+
+
+
+sub MAIN( Int $S where { $S > 0 },
+          *@C where { @C.grep( * ~~ Int ).elems == @C.elems } ) {
+    say "Coins are { @C } that must give sum $S";
+
+    my @solutions;
+
+    @solutions = find-solutions( coins => @C, sum => $S );
+
+    @solutions.join( "\n" ).say;
+
+}