2 files changed, 79 insertions, 0 deletions
diff --git a/challenge-113/feng-chang/raku/ch-1.raku b/challenge-113/feng-chang/raku/ch-1.raku
new file mode 100755
index 0000000000..3b3e4cb4b1
--- /dev/null
+++ b/challenge-113/feng-chang/raku/ch-1.raku
@@ -0,0 +1,11 @@
+#!/bin/env raku
+
+subset Digit of UInt where * ≤ 9;
+
+sub MAIN(UInt:D $N = 25, Digit:D $D = 7) {
+    put do given $N {
+        when $N ~~ /$D/                                      { 1 }
+        when $N == (1..^$N).grep(/$D/).combinations».sum.any { 1 }
+        default                                              { 0 }
+    }
+}
diff --git a/challenge-113/feng-chang/raku/ch-2.raku b/challenge-113/feng-chang/raku/ch-2.raku
new file mode 100755
index 0000000000..0a25d20ea9
--- /dev/null
+++ b/challenge-113/feng-chang/raku/ch-2.raku
@@ -0,0 +1,68 @@
+#!/bin/env raku
+
+grammar Tree {
+    rule  TOP  { '(' <node> <TOP> ** 0..2 ')' }
+    token node { \d+ }
+}
+
+class TreeActions {
+    method TOP($/) {
+        my %h = root => $<node>.made;
+        %h<left>  = $<TOP>[0].made if $<TOP>[0];
+        %h<right> = $<TOP>[1].made if $<TOP>[1];
+
+        make %h;
+    }
+
+    method node($/) { make $/.Int }
+}
+
+multi MAIN('test') {
+    use Test;
+
+    is-deeply Tree.parse('(111)', :actions(TreeActions)).made, { root => 111 }, '(111) parsed';
+    is-deeply
+        Tree.parse('(6 (2) (3))', :actions(TreeActions)).made,
+        { root => 6, left => { root => 2 }, right => { root => 3 } },
+        '(6 (2) (3)) parsed';
+
+    done-testing;
+}
+
+sub tree-sum($t --> Int:D) {
+    $t ?? $t<root> + tree-sum($t<left>) + tree-sum($t<right>) !! 0
+}
+
+sub modify-tree($t, Int:D $sum) {
+    return unless $t;
+
+    $t<root> = $sum - $t<root>;
+    modify-tree($t<left>,  $sum);
+    modify-tree($t<right>, $sum);
+}
+
+sub print-tree(Hash:D $t) {
+    print '(', $t<root>;
+
+    if $t<left>.defined {
+        print ' ';
+        print-tree($t<left>);
+    }
+
+    if $t<right>.defined {
+        print ' ';
+        print-tree($t<right>);
+    }
+
+    print ')';
+}
+
+multi MAIN(Str:D $t = '(1(2(4(7)))(3(5)(6)))') {
+    my Hash $tree .= new(Tree.parse($t, :actions(TreeActions)).made);
+
+    my $sum = tree-sum($tree);
+    modify-tree($tree, $sum);
+
+    print-tree($tree);
+    put '';
+}