challenge 143, raku solutions

2 files changed, 78 insertions, 0 deletions

diff --git a/challenge-143/feng-chang/raku/ch-1.raku b/challenge-143/feng-chang/raku/ch-1.raku
new file mode 100755
index 0000000000..2ba225b57f
--- /dev/null
+++ b/challenge-143/feng-chang/raku/ch-1.raku
@@ -0,0 +1,63 @@
+#!/bin/env raku
+
+use MONKEY-SEE-NO-EVAL;
+
+grammar Expression {
+    rule TOP { <expression> }
+
+    rule expression { <term>+ % <add-op> }
+    rule term       { <item>+ % <mul-op> }
+    rule item       { || '(' <expression> ')' || <number> }
+
+    token add-op { '+' | '-' }
+    token mul-op { '*' | '/' }
+    token number { \d+ }
+}
+
+class ExpressionActions {
+    method TOP($/) { make $<expression>.made }
+
+    method expression($/) {
+        my $n = $<term>[0].made;
+        for $<add-op>».made Z $<term>[1..*]».made -> (\op, \term) {
+            given op {
+                when '+' { $n += term }
+                when '-' { $n -= term }
+            }
+        }
+        make $n;
+    }
+
+    method term($/) {
+        my $n = $<item>[0].made;
+        for $<mul-op>».made Z $<item>[1..*]».made -> (\op, \item) {
+            given op {
+                when '*' { $n   *= item }
+                when '/' { $n div= item }
+            }
+        }
+        make $n;
+    }
+
+    method item($/) { make $<expression>.defined ?? $<expression>.made !! $<number>.made }
+
+    method add-op($/) { make $/.Str }
+    method mul-op($/) { make $/.Str }
+    method number($/) { make $/.Int }
+}
+
+my Str $s;
+
+use Test;
+
+repeat {
+    $s = prompt 'Please enter an arithmetic expression: ';
+    { put ''; last } unless $s;
+
+    my $er = (EVAL $s).Int;
+    my $gr = Expression.parse($s, :actions(ExpressionActions)).made;
+
+    is $er, $gr, "'$s' = $gr, EVAL agrees with Grammar";
+} while $s.chars > 0;
+
+done-testing;
diff --git a/challenge-143/feng-chang/raku/ch-2.raku b/challenge-143/feng-chang/raku/ch-2.raku
new file mode 100755
index 0000000000..5f561558ac
--- /dev/null
+++ b/challenge-143/feng-chang/raku/ch-2.raku
@@ -0,0 +1,15 @@
+#!/bin/env raku
+
+unit sub MAIN(UInt:D \n);
+
+sub is-stealthy(UInt:D \n --> Bool:D) {
+    (1..sqrt(n).Int)
+        .grep(n %% *)
+        .map({ [$_, n div $_] })
+        .combinations(2)
+        .grep({ abs(.[0].sum - .[1].sum) == 1 })
+        .elems
+    > 0
+}
+
+put +is-stealthy(n);