challeng#079, raku solutions

4 files changed, 24 insertions, 14 deletions

diff --git a/challenge-077/feng-chang/raku/ch-1.raku b/challenge-077/feng-chang/raku/ch-1.raku
index 18676223f9..053b739a43 100755
--- a/challenge-077/feng-chang/raku/ch-1.raku
+++ b/challenge-077/feng-chang/raku/ch-1.raku
@@ -3,26 +3,29 @@
 my Bool $found = False;
 my $Num;
 
+# $N:    = (intial N) - @num.sum
+# @fibs: fibonacci numbers as candidates
+# @num:  solution
 sub fib-sum(Int:D $N, @fibs, @num) {
     if $N == 0 {
         say "{ @num.join(' + ') } = $Num";
         $found = True;
         return;
     }
-    return unless @fibs;
-    return if $N < @fibs[0];
+    return unless @fibs;        # all fibonacci numbers are exhausted
+    return if $N < @fibs[0];    # impossible to find a solution
 
     my @F = @fibs;
     my @N = @num;
     @N.push(@F.shift);
-    fib-sum($N - @fibs[0], @F, @N);
+    fib-sum($N - @fibs[0], @F, @N);     # try all possibilities that includes current candidate
 
-    fib-sum($N, @F, @num);
+    fib-sum($N, @F, @num);              # try all possibilities that excludes current candidate
 }
 
 sub MAIN(Int:D $N) {
     my Int @fibs = 1, 2, * + * ...^ * > $N;
-    $Num = $N;
+    $Num = $N;      # remember the initial N
 
     fib-sum($N, @fibs, Array.new);
     0.say unless $found;
diff --git a/challenge-077/feng-chang/raku/ch-2.raku b/challenge-077/feng-chang/raku/ch-2.raku
index b9fdf10332..04c51308ff 100755
--- a/challenge-077/feng-chang/raku/ch-2.raku
+++ b/challenge-077/feng-chang/raku/ch-2.raku
@@ -1,7 +1,8 @@
 #!/bin/env raku
 
+# read input and surround matrix with O's
+#   e.g.: ./ch-2.raku < data-c2-01.txt
 my @a;
-
 for $*IN.lines -> $line {
     @a.push($line.comb.Array.unshift('O').push('O'));
 }
@@ -11,15 +12,14 @@ my UInt $width = @a[0].elems - 2;
 @a.unshift(['O' xx $width + 2]);;
 @a.push(['O' xx $width + 2]);;
 
+# count lonely X's
 my UInt $cnt = 0;
-for 1..$rows -> $i {
-    for 1..$width -> $j {
-        my $junc = all(@a[$i-1;$j-1], @a[$i-1;$j], @a[$i-1;$j+1],
-                       @a[$i;$j-1],                @a[$i;$j+1],
-                       @a[$i+1;$j-1], @a[$i+1;$j], @a[$i+1;$j+1]
-                   );
-        ++$cnt if @a[$i;$j] eq 'X' and $junc eq 'O';
-    }
+for 1..$rows X 1..$width -> ($i, $j) {
+    my $junc = all(@a[$i-1;$j-1], @a[$i-1;$j], @a[$i-1;$j+1],
+                   @a[$i;$j-1],                @a[$i;$j+1],
+                   @a[$i+1;$j-1], @a[$i+1;$j], @a[$i+1;$j+1]
+               );
+    ++$cnt if @a[$i;$j] eq 'X' and $junc eq 'O';
 }
 
 say $cnt;
diff --git a/challenge-077/feng-chang/raku/data-c2-01.txt b/challenge-077/feng-chang/raku/data-c2-01.txt
new file mode 100644
index 0000000000..32e25b69b9
--- /dev/null
+++ b/challenge-077/feng-chang/raku/data-c2-01.txt
@@ -0,0 +1,3 @@
+OOX
+XOO
+XOO
diff --git a/challenge-077/feng-chang/raku/data-c2-02.txt b/challenge-077/feng-chang/raku/data-c2-02.txt
new file mode 100644
index 0000000000..600d69c9a9
--- /dev/null
+++ b/challenge-077/feng-chang/raku/data-c2-02.txt
@@ -0,0 +1,4 @@
+OOXO
+XOOO
+XOOX
+OXOO