langs a-z

Task/Average-loop-length/Perl-6/average-loop-length.pl6

@@ -0,0 +1,18 @@
+constant MAX_N  = 20;
+constant TRIALS = 100;
+
+for 1 .. MAX_N -> $N {
+    my $empiric = TRIALS R/ [+] find-loop(random-mapping($N)).elems xx TRIALS;
+    my $theoric = [+]
+        map -> $k { $N ** ($k + 1) R/ [*] $k**2, $N - $k + 1 .. $N }, 1 .. $N;
+
+    FIRST say " N    empiric      theoric      (error)";
+    FIRST say "===  =========  ============  =========";
+
+    printf "%3d  %9.4f  %12.4f    (%4.2f%%)\n",
+            $N,  $empiric,
+                        $theoric, 100 * abs($theoric - $empiric) / $theoric;
+}
+
+sub random-mapping { hash .list Z=> .roll given ^$^size }
+sub find-loop { 0, %^mapping{*} ...^ { (state %){$_}++ } }