Merge pull request #4054 from seaker/master

challenge 112, Feng Chang's raku solutions

2 files changed, 38 insertions, 0 deletions

diff --git a/challenge-112/feng-chang/raku/ch-1.raku b/challenge-112/feng-chang/raku/ch-1.raku
new file mode 100755
index 0000000000..cf4cf08e00
--- /dev/null
+++ b/challenge-112/feng-chang/raku/ch-1.raku
@@ -0,0 +1,23 @@
+#!/bin/env raku
+
+sub MAIN(Str:D $path where * ~~ rx{^'/'}) {
+    my @dirs = $path.split(rx{'/'+}).tail(*-1);     # put all directory names into an array, omit first empty element
+    @dirs.pop unless @dirs[*-1];                    # omit last element if it is empty
+    my $i = 0;
+    try {
+        while $i < @dirs.elems {
+            given @dirs[$i] {
+                when '.'  { @dirs.splice($i, 1) }           # omit '.'
+                when '..' { @dirs.splice($i-1, 2); --$i; }  # omit '..' and its upper directory
+                default   { ++$i }
+            }
+        }
+
+        CATCH {
+            $*ERR.put: 'cannot walk beyond root';   # guard against excessive '..'s
+            exit;
+        }
+    }
+
+    put '/', @dirs.join('/');
+}
diff --git a/challenge-112/feng-chang/raku/ch-2.raku b/challenge-112/feng-chang/raku/ch-2.raku
new file mode 100755
index 0000000000..b674d7b518
--- /dev/null
+++ b/challenge-112/feng-chang/raku/ch-2.raku
@@ -0,0 +1,15 @@
+#!/bin/env raku
+
+proto walk(UInt:D --> UInt:D) {*}   # restrict dispatch pattern
+
+multi walk(0)  { 1 }
+multi walk(1)  { 1 }
+multi walk(2)  { 2 }
+
+multi walk($n) {
+    state @memo;                    # use memory to speed up counting
+    @memo[$n] = walk($n-1) + walk($n-2) unless @memo[$n].defined;
+    @memo[$n];
+}
+
+sub MAIN(UInt:D $n) { put walk($n) }