Linked lists are fun?

1 files changed, 74 insertions, 0 deletions

diff --git a/challenge-068/simon-proctor/raku/ch-2.raku b/challenge-068/simon-proctor/raku/ch-2.raku
new file mode 100644
index 0000000000..226b5c2121
--- /dev/null
+++ b/challenge-068/simon-proctor/raku/ch-2.raku
@@ -0,0 +1,74 @@
+#!/usr/bin/env raku
+
+class ListNode {
+    has $.value;
+    has ListNode $!next;
+
+    method is-last() {
+        ! $!next.defined;
+    }
+
+    method next() {
+        $!next;
+    }
+    
+    method add-next( ListNode $next ) {
+         $!next = $next;
+    }
+
+    method move-node( ListNode $start, ListNode $node ) {
+        my $prev = $start;
+        my $next = $!next;
+        my $node-next = $node.next;
+        while $prev.next !~~ $node { $prev = $prev.next }
+        $!next = $node;
+        $node.add-next( $next );
+        $prev.add-next( $node-next );
+    }
+    
+    method gist() {
+        if self.is-last {
+            "$.value";
+        } else  {
+            "{$.value} -> {$!next.gist}";
+        }
+    }
+
+    method from-iterator( ListNode:U : @values ) {
+        my ( $start-node, $node );
+        
+        for @values -> $value {
+            if ! $start-node.defined {
+                $start-node = ListNode.new( :$value );
+                $node = $start-node;
+            } else {
+                my $next-node = ListNode.new( :$value );
+                $node.add-next( $next-node );
+                $node = $next-node;
+            }        
+        }
+        return $start-node;
+    }
+
+    method last-node() {
+        my $node = self;
+        while ! $node.is-last { $node = $node.next(); }
+        return $node;
+    }
+}
+
+sub MAIN( *@values where *.elems >= 1 ) {
+    my $start-node = ListNode.from-iterator( @values );
+    say "Input  : {$start-node.gist}";
+    my $end-node = $start-node.last-node;
+    my $current-node = $start-node;
+    while ! $current-node.is-last {
+        my $next-node = $current-node.next;
+        if ! $next-node.is-last {
+            $current-node.move-node( $start-node, $end-node );
+            $end-node = $current-node.last-node;
+        }
+        $current-node = $next-node;
+    }
+    say "Output : {$start-node.gist}";
+}