Task 1 NodeJS soln, Task 1 & 2 Perl soln

3 files changed, 122 insertions, 0 deletions

diff --git a/challenge-174/cheok-yin-fung/node/ch-1.js b/challenge-174/cheok-yin-fung/node/ch-1.js
new file mode 100644
index 0000000000..9259b4f334
--- /dev/null
+++ b/challenge-174/cheok-yin-fung/node/ch-1.js
@@ -0,0 +1,29 @@
+// The Weekly Challenge 174
+// Task 1 Disarium Numbers
+// Node.js Solution
+
+let disar = 0;     
+for (let n=0; n < 9999999; n++) {
+  let total = 0;
+  for([i, v] of n.toString().split("").entries()) {
+    total += v**(i+1);
+  }
+  if (total === n) {
+    console.log(n);
+    disar++;
+  }
+  if (disar===19) {break;}
+}
+
+
+/* 0 to 9
+89
+135
+175
+518
+598
+1306
+1676
+2427
+2646798
+*/
diff --git a/challenge-174/cheok-yin-fung/perl/ch-1.pl b/challenge-174/cheok-yin-fung/perl/ch-1.pl
new file mode 100644
index 0000000000..9ac06ce057
--- /dev/null
+++ b/challenge-174/cheok-yin-fung/perl/ch-1.pl
@@ -0,0 +1,31 @@
+#!/usr/bin/perl
+# The Weekly Challenge 174
+# Task 1 Disarium Numbers
+use v5.30.0;
+use warnings;
+
+my $d = 0;
+my $n = 0;
+while ($d < 19) {
+    my @arr = split "", $n;
+    my $total = 0;
+    $total += $arr[$_]**($_+1) for 0..$#arr;
+    if ($total == $n) {
+        say $n;
+        $d++;
+    }
+    $n++;
+}
+
+=pod
+0 to 9
+89
+135
+175
+518
+598
+1306
+1676
+2427
+2646798
+
diff --git a/challenge-174/cheok-yin-fung/perl/ch-2.pl b/challenge-174/cheok-yin-fung/perl/ch-2.pl
new file mode 100644
index 0000000000..f0fb2df3e6
--- /dev/null
+++ b/challenge-174/cheok-yin-fung/perl/ch-2.pl
@@ -0,0 +1,62 @@
+# The Weekly Challenge 174
+# Task 2 Permutation Ranking
+# O(n^2) solution, translation of Python code on
+# https://tryalgo.org/en/permutations/2016/09/05/permutation-rank/
+use v5.30.0;
+use warnings;
+use List::Util qw/first/;
+
+
+
+sub factorial {
+    my $ans = 1;
+    for (1..$_[0]) {
+       $ans *= $_; 
+    }
+    return $ans;
+}
+
+
+
+sub permutation2rank {
+    my @list = $_[0]->@*;
+    my $n = scalar @list;
+    my $fact = factorial($n-1);
+    my $r = 0;
+    my @unused_list = sort {$a<=>$b} @list;
+    for my $i (0..$n-2) {
+        my $q = first { $unused_list[$_] == $list[$i] } 0..$#unused_list;
+        $r += $q*$fact;
+        splice @unused_list, $q, 1;
+        $fact = int $fact / ($n-$i-1);
+    }
+    return $r;
+}
+
+
+
+sub rank2permutation {
+    my @list = $_[0]->@*;
+    my $r = $_[1];
+    my $n = scalar @list;
+    my $fact = factorial($n-1);
+    my @unused_list = sort {$a<=>$b} @list;
+    my @p = ();
+    for my $i (0..$n-1) {
+        my $q = int $r / $fact;
+        $r %= $fact;
+        push @p, $unused_list[$q];
+        splice @unused_list, $q, 1;
+        $fact = int $fact / ($n-1-$i) if $i != $n-1;
+    }
+    return [@p];
+}
+
+
+
+use Test::More tests=>3;
+use Test::Deep;
+ok permutation2rank([1,3,2,4,5]) == 6;
+cmp_deeply rank2permutation([1,6,9],3), [6,9,1];
+ok permutation2rank([9,7,5,3,1]) == 119;
+