2 files changed, 80 insertions, 0 deletions
diff --git a/challenge-174/wambash/raku/ch-1.raku b/challenge-174/wambash/raku/ch-1.raku
new file mode 100644
index 0000000000..6d06638635
--- /dev/null
+++ b/challenge-174/wambash/raku/ch-1.raku
@@ -0,0 +1,20 @@
+#!/usr/bin/env raku
+
+sub is-disarium-number ($n) {
+    $n == [+] $n.comb Z** 1 .. *
+}
+
+multi MAIN (Bool :test($)!) {
+    use Test;
+    is is-disarium-number($_),True, "$_ is disarium" for 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 89, 135, 175, 518, 598, 1306, 1676, 2427, 2646798, 12157692622039623539;
+    is is-disarium-number($_),False, "$_ is not disarium" for 10, 134, 577;
+    done-testing;
+}
+
+multi MAIN (UInt $k=19) {
+    ^∞
+    andthen .hyper
+    andthen .grep: &is-disarium-number
+    andthen .head: $k
+    andthen .Supply.tap: *.put
+}
diff --git a/challenge-174/wambash/raku/ch-2.raku b/challenge-174/wambash/raku/ch-2.raku
new file mode 100644
index 0000000000..2481005720
--- /dev/null
+++ b/challenge-174/wambash/raku/ch-2.raku
@@ -0,0 +1,60 @@
+#!/usr/bin/env raku
+
+sub iter-perm2rank ( Capture ( :@perm, :@seq=Empty  ) ) {
+    my $h := @perm.head;
+    \(
+        :perm( |@perm.skip.map: {$_ - ($_ > $h)} ),
+        :seq( $h, |@seq ),
+    )
+}
+
+sub iter-rank2perm (Capture (:@seq, :@adepts,:@perm = Empty)) {
+    my $h = @seq.head;
+    \(
+        :seq( @seq.skip ),
+        :adepts( |@adepts.head($h), |@adepts.skip( $h+1 ) ),
+        :perm( |@perm, @adepts[$h] ),
+    )
+}
+
+sub permutation2rank (+@perm) {
+    \( :@perm, ), &iter-perm2rank ... *.<perm>.elems == 0
+    andthen .tail
+    andthen .<seq>
+    andthen .skip Z* [\*] 1..∞
+    andthen .sum
+}
+
+sub rank2permutation ($rank, $n) {
+    $rank
+    andthen .polymod: 1..$n
+    andthen \(:seq(.reverse.skip),:adepts(^$n) ), &iter-rank2perm ... *.<adepts>.elems == 0
+    andthen .tail.<perm>
+}
+
+multi MAIN (Bool :test($)!) {
+    use Test;
+    is iter-rank2perm( \(:seq(1,1),:adepts(^3)) ).<adepts>, (0,2);
+    is iter-perm2rank( \(:perm(1,2,0))  ).<perm>, (1,0);
+    is permutation2rank(0,1,2,3,4),0;
+    is rank2permutation(4,5), (0,1,4,2,3);
+    for 1..5 {
+        subtest {
+            is permutation2rank(.value),.key, $_ for permutations(^$_).pairs;
+        }, "perm2rank n=$_";
+    }
+    for 1..5 -> $n {
+        subtest {
+            is rank2permutation(.key, $n),.value, $_ for permutations(^$n).pairs;
+        }, "perm2rank n=$n";
+    }
+    subtest {
+        is permutation2rank(rank2permutation($_, 20)), $_ for  (1 .. [*] 1..20).roll(4)
+    }, "perm2rank rank2perm n=20 (random)";
+
+    done-testing;
+}
+
+multi MAIN ( $k,$n=10 ) {
+    say  rank2permutation $k, $n
+}