Merge remote-tracking branch 'upstream/master'

11 files changed, 983 insertions, 11 deletions

diff --git a/challenge-175/athanasius/perl/ch-1.pl b/challenge-175/athanasius/perl/ch-1.pl
new file mode 100644
index 0000000000..bf4458cf4f
--- /dev/null
+++ b/challenge-175/athanasius/perl/ch-1.pl
@@ -0,0 +1,148 @@
+#!perl
+
+###############################################################################
+=comment
+
+Perl Weekly Challenge 175
+=========================
+
+TASK #1
+-------
+*Last Sunday*
+
+Submitted by: Mohammad S Anwar
+
+Write a script to list Last Sunday of every month in the given year.
+
+For example, for year 2022, we should get the following:
+
+  2022-01-30
+  2022-02-27
+  2022-03-27
+  2022-04-24
+  2022-05-29
+  2022-06-26
+  2022-07-31
+  2022-08-28
+  2022-09-25
+  2022-10-30
+  2022-11-27
+  2022-12-25
+
+=cut
+###############################################################################
+
+#--------------------------------------#
+# Copyright © 2022 PerlMonk Athanasius #
+#--------------------------------------#
+
+#==============================================================================
+=comment
+
+Assumptions
+-----------
+All dates are interpreted according to the Gregorian calendar [1,3]. Dates
+prior to 15th October, 1582, when the Gregorian calendar was first introduced,
+are calculated according to the "proleptic Gregorian calendar" [3] which
+extends backwards to dates before the calendar was in use. However, dates prior
+to the year 1 AD are not supported.
+
+Solution
+--------
+The solution uses the CPAN module DateTime [2]. Its last_day_of_month()
+constructor automatically finds the last day of February as 28 or 29, according
+to whether or not the year is a leap year.
+
+Then, DateTime's day_of_the_week() method finds the weekday of the last day in
+the month: it "[r]eturns the day of the week as a number, from 1..7, with 1
+being Monday and 7 being Sunday." [2] If the last day is a Monday, then the
+last Sunday is one day prior; if a Tuesday, it is two days prior; and so on.
+Hence, the date of the last Sunday is calculated by subtracting from the date
+of the last day the weekday of the last day modulo 7.
+
+References
+----------
+[1]  Claus Tøndering, "The Gregorian calendar", The Calendar FAQ,
+     https://www.tondering.dk/claus/cal/gregorian.php
+[2]  Dave Rolsky, "DateTime", MetaCPAN, https://metacpan.org/pod/DateTime
+[3] "Gregorian calendar", Wikipedia,
+     https://en.wikipedia.org/wiki/Gregorian_calendar
+
+=cut
+#==============================================================================
+
+use strict;
+use warnings;
+use Const::Fast;
+use DateTime;
+use Regexp::Common qw( number );
+
+const my $USAGE =>
+"Usage:
+  perl $0 <year>
+
+    <year>    A year in the Gregorian calendar (AD)\n";
+
+#------------------------------------------------------------------------------
+BEGIN
+#------------------------------------------------------------------------------
+{
+    $| = 1;
+    print "\nChallenge 175, Task #1: Last Sunday (Perl)\n\n";
+}
+
+#==============================================================================
+MAIN:
+#==============================================================================
+{
+    my $year = parse_command_line();
+
+    print "The last Sunday of each month in the year $year:\n\n";
+
+    for my $month (1 .. 12)
+    {
+        my $last_day_dt = DateTime->last_day_of_month
+                          (
+                              year  => $year,
+                              month => $month,
+                          );
+        my $last_day    = $last_day_dt->day;
+        my $day_of_week = $last_day_dt->day_of_week;
+        my $last_sun_dt = DateTime->new
+                          (
+                              year  => $year,
+                              month => $month,
+                              day   => $last_day - ($day_of_week % 7),
+                          );
+        
+        printf "  %s\n", $last_sun_dt->ymd;
+    }
+}
+
+#------------------------------------------------------------------------------
+sub parse_command_line
+#------------------------------------------------------------------------------
+{
+    my $args = scalar @ARGV;
+       $args == 1 or error( "Expected 1 command line argument, found $args" );
+
+    my $year = $ARGV[ 0 ];
+
+    $year =~ / ^ $RE{num}{int} $ /x
+                  or error( qq[Argument "$year" is not a valid integer] );
+
+    $year >= 1    or error( qq[Year "$year" is not AD] );
+
+    return $year;
+}
+
+#------------------------------------------------------------------------------
+sub error
+#------------------------------------------------------------------------------
+{
+    my ($message) = @_;
+
+    die "ERROR: $message\n$USAGE";
+}
+
+###############################################################################
diff --git a/challenge-175/athanasius/perl/ch-2.pl b/challenge-175/athanasius/perl/ch-2.pl
new file mode 100644
index 0000000000..d2f832d4aa
--- /dev/null
+++ b/challenge-175/athanasius/perl/ch-2.pl
@@ -0,0 +1,142 @@
+#!perl
+
+###############################################################################
+=comment
+
+Perl Weekly Challenge 175
+=========================
+
+TASK #2
+-------
+*Perfect Totient Numbers*
+
+Submitted by: Mohammad S Anwar
+
+Write a script to generate first 20 Perfect Totient Numbers. Please checkout
+[ https://en.wikipedia.org/wiki/Perfect_totient_number |wikipedia page] for
+more informations.
+
+Output
+
+  3, 9, 15, 27, 39, 81, 111, 183, 243, 255, 327, 363, 471, 729,
+  2187, 2199, 3063, 4359, 4375, 5571
+
+=cut
+###############################################################################
+
+#--------------------------------------#
+# Copyright © 2022 PerlMonk Athanasius #
+#--------------------------------------#
+
+#==============================================================================
+=comment
+
+Totients and Iterated Totients
+------------------------------
+"In number theory, Euler's totient function counts the positive integers up to
+a given integer n that are relatively prime to n. ... In other words, it is the
+number of integers k in the range 1 ≤ k ≤ n for which the greatest common
+divisor gcd(n, k) is equal to 1." [5] For all n > 2, φ(n) is even.
+
+Since gcd(n, n) = n, it follows that, for all n > 1, φ(n) is at most n - 1
+(when happens when n is prime), so φ(n) < n. So when totients are iterated, the
+iterations always eventually decrease to 2, and then to 1.
+
+Perfect Totient Numbers
+-----------------------
+AFAICT, the definitions of Perfect Totient Numbers (PTNs) given in [6] and [2]
+imply that 1 is a PTN, which it is not. A more rigorous definition is given in
+[4], which specifies that a PTN must be > 2.
+
+"It is trivial that perfect totient numbers must be odd. It is easy to show
+that powers of 3 are perfect totient numbers." [2]
+
+Solution
+--------
+The CPAN module Math::Prime::Util [3] provides function euler_phi(), which cal-
+culates the totient of a given integer very quickly. (For a home-grown imple-
+mentation of euler_phi(), see the Raku solution to Task 2.)
+
+Subroutine iterated_totient_sum() calls euler_phi() repeatedly until the itera-
+tions reduce to 2. The iterations are summed progressively, and finally 1 is
+added for φ(2).
+
+The main routine calls iterated_totient_sum() repeatedly on successive odd
+numbers: those for which the iterated totient sum equals the number itself are
+PTNs. The search continues until $TARGET PTNs have been found and displayed.
+
+References
+----------
+[1] "A000010  Euler totient function phi(n): count numbers <= n and prime to
+     n.", OEIS, https://oeis.org/A000010
+[2] "A082897  Perfect totient numbers.", OEIS, https://oeis.org/A082897
+[3]  Dana Jacobsen, "Math::Prime::Util", MetaCPAN,
+     https://metacpan.org/pod/Math::Prime::Util
+[4]  Douglas E. Iannucci, Deng Moujie, and Graeme L. Cohen, "On Perfect Totient
+     Numbers", Journal of Integer Sequences, Vol. 6 (2003),
+     http://www.emis.de/journals/JIS/VOL6/Cohen2/cohen50.pdf
+[5] "Euler's totient function", Wikipedia,
+     https://en.wikipedia.org/wiki/Euler%27s_totient_function
+[6] "Perfect totient number", Wikipedia,
+     https://en.wikipedia.org/wiki/Perfect_totient_number
+
+=cut
+#==============================================================================
+
+use strict;
+use warnings;
+use Const::Fast;
+use Math::Prime::Util qw( euler_phi );
+
+const my $TARGET => 20;
+const my $USAGE  => "Usage:\n  perl $0\n";
+
+#------------------------------------------------------------------------------
+BEGIN
+#------------------------------------------------------------------------------
+{
+    $| = 1;
+    print "\nChallenge 175, Task #2: Perfect Totient Numbers (Perl)\n\n";
+}
+
+#==============================================================================
+MAIN:
+#==============================================================================
+{
+    my $args = scalar @ARGV;
+       $args == 0 or die 'ERROR: Expected 0 command line arguments, found ' .
+                         "$args\n$USAGE";
+
+    print "The first $TARGET Perfect Totient Numbers:\n\n3";
+
+    my $count = 1;
+
+    for (my $n = 5; $count < $TARGET; $n += 2)
+    {
+        if (iterated_totient_sum( $n ) == $n)
+        {
+            print ", $n";
+            ++$count;
+        }
+    }
+
+    print "\n";
+}
+
+#------------------------------------------------------------------------------
+sub iterated_totient_sum
+#------------------------------------------------------------------------------
+{
+    my ($n)  = @_;
+    my  $sum = 0;
+
+    while ($n > 2)
+    {
+        $n    = euler_phi( $n );
+        $sum += $n;
+    }
+
+    return ++$sum;      # euler_phi(2) = 1
+}
+
+###############################################################################
diff --git a/challenge-175/athanasius/raku/ch-1.raku b/challenge-175/athanasius/raku/ch-1.raku
new file mode 100644
index 0000000000..81586e5826
--- /dev/null
+++ b/challenge-175/athanasius/raku/ch-1.raku
@@ -0,0 +1,111 @@
+use v6d;
+
+###############################################################################
+=begin comment
+
+Perl Weekly Challenge 175
+=========================
+
+TASK #1
+-------
+*Last Sunday*
+
+Submitted by: Mohammad S Anwar
+
+Write a script to list Last Sunday of every month in the given year.
+
+For example, for year 2022, we should get the following:
+
+  2022-01-30
+  2022-02-27
+  2022-03-27
+  2022-04-24
+  2022-05-29
+  2022-06-26
+  2022-07-31
+  2022-08-28
+  2022-09-25
+  2022-10-30
+  2022-11-27
+  2022-12-25
+
+=end comment
+###############################################################################
+
+#--------------------------------------#
+# Copyright © 2022 PerlMonk Athanasius #
+#--------------------------------------#
+
+#==============================================================================
+=begin comment
+
+Assumptions
+-----------
+All dates are interpreted according to the Gregorian calendar [2,3]. Dates
+prior to 15th October, 1582, when the Gregorian calendar was first introduced,
+are calculated according to the "proleptic Gregorian calendar" [3] which
+extends backwards to dates before the calendar was in use. However, dates prior
+to the year 1 AD are not supported.
+
+Solution
+--------
+The solution uses Raku's native Date class [1]. Its constructor accepts a "*"
+as the argument to its "day" parameter: this gives the last day in the month,
+automatically finding the last day of February as 28 or 29, according to
+whether or not the year is a leap year.
+
+Then, Date's day-of-week() method finds the weekday of the last day in the
+month: it "[r]eturns the day of the week, where 1 is Monday, 2 is Tuesday and
+Sunday is 7." [1] If the last day is a Monday, then the last Sunday is one day
+prior; if a Tuesday, it is two days prior; and so on. Hence, the date of the
+last Sunday is calculated by subtracting from the date of the last day the
+weekday of the last day modulo 7.
+
+References
+----------
+[1] "class Date", Raku Documentation, https://docs.raku.org/type/Date
+[2]  Claus Tøndering, "The Gregorian calendar", The Calendar FAQ,
+     https://www.tondering.dk/claus/cal/gregorian.php
+[3] "Gregorian calendar", Wikipedia,
+     https://en.wikipedia.org/wiki/Gregorian_calendar
+
+=end comment
+#==============================================================================
+
+#------------------------------------------------------------------------------
+BEGIN
+#------------------------------------------------------------------------------
+{
+    "\nChallenge 175, Task #1: Last Sunday (Raku)\n".put;
+}
+
+#==============================================================================
+sub MAIN
+(
+    UInt:D $year where * > 0           #= A year in the Gregorian calendar (AD)
+)
+#==============================================================================
+{
+    "The last Sunday of each month in the year $year:\n".put;
+
+    for 1 .. 12 -> UInt $month
+    {
+        my Date $last-day = Date.new: $year, $month, *;
+        my Date $last-sun = Date.new: $last-day - ($last-day.day-of-week % 7);
+
+        "  { $last-sun.Str }".put;
+    }
+}
+
+#------------------------------------------------------------------------------
+sub USAGE()
+#------------------------------------------------------------------------------
+{
+    my Str $usage = $*USAGE;
+
+    $usage ~~ s/ ($*PROGRAM-NAME) /raku $0/;
+
+    $usage.put;
+}
+
+###############################################################################
diff --git a/challenge-175/athanasius/raku/ch-2.raku b/challenge-175/athanasius/raku/ch-2.raku
new file mode 100644
index 0000000000..dea3154069
--- /dev/null
+++ b/challenge-175/athanasius/raku/ch-2.raku
@@ -0,0 +1,188 @@
+use v6d;
+
+###############################################################################
+=begin comment
+
+Perl Weekly Challenge 175
+=========================
+
+TASK #2
+-------
+*Perfect Totient Numbers*
+
+Submitted by: Mohammad S Anwar
+
+Write a script to generate first 20 Perfect Totient Numbers. Please checkout
+[ https://en.wikipedia.org/wiki/Perfect_totient_number |wikipedia page] for
+more informations.
+
+Output
+
+  3, 9, 15, 27, 39, 81, 111, 183, 243, 255, 327, 363, 471, 729,
+  2187, 2199, 3063, 4359, 4375, 5571
+
+=end comment
+###############################################################################
+
+#--------------------------------------#
+# Copyright © 2022 PerlMonk Athanasius #
+#--------------------------------------#
+
+#==============================================================================
+=begin comment
+
+Totients and Iterated Totients
+------------------------------
+"In number theory, Euler's totient function counts the positive integers up to
+a given integer n that are relatively prime to n. ... In other words, it is the
+number of integers k in the range 1 ≤ k ≤ n for which the greatest common
+divisor gcd(n, k) is equal to 1." [5] For all n > 2, φ(n) is even.
+
+Since gcd(n, n) = n, it follows that, for all n > 1, φ(n) is at most n - 1
+(when happens when n is prime), so φ(n) < n. So when totients are iterated, the
+iterations always eventually decrease to 2, and then to 1.
+
+Perfect Totient Numbers
+-----------------------
+AFAICT, the definitions of Perfect Totient Numbers (PTNs) given in [6] and [2]
+imply that 1 is a PTN, which it is not. A more rigorous definition is given in
+[4], which specifies that a PTN must be > 2.
+
+"It is trivial that perfect totient numbers must be odd. It is easy to show
+that powers of 3 are perfect totient numbers." [2]
+
+Solution
+--------
+Function euler-phi() calculates φ(n) using Euler's product formula [5]:
+
+  φ(n) = n ∏ (1 - 1/p)   where p ranges over the distinct primes that divide n.
+
+The prime factors of n are calculated by the recursive function prime-factors()
+which in turn uses Raku's native is-prime() method.
+
+Subroutine iterated-totient-sum() calls euler-phi() repeatedly until the itera-
+tions reduce to 2. The iterations are summed progressively, and finally 1 is
+added for φ(2).
+
+The main routine calls iterated-totient-sum() repeatedly on successive odd
+numbers: those for which the iterated totient sum equals the number itself are
+PTNs. The search continues until $TARGET PTNs have been found and displayed.
+For $TARGET = 20, the complete search takes 14 seconds on my machine.
+
+References
+----------
+[1] "A000010  Euler totient function phi(n): count numbers <= n and prime to
+     n.", OEIS, https://oeis.org/A000010
+[2] "A082897  Perfect totient numbers.", OEIS, https://oeis.org/A082897
+[3]  Dana Jacobsen, "Math::Prime::Util", MetaCPAN,
+     https://metacpan.org/pod/Math::Prime::Util
+[4]  Douglas E. Iannucci, Deng Moujie, and Graeme L. Cohen, "On Perfect Totient
+     Numbers", Journal of Integer Sequences, Vol. 6 (2003),
+     http://www.emis.de/journals/JIS/VOL6/Cohen2/cohen50.pdf
+[5] "Euler's totient function", Wikipedia,
+     https://en.wikipedia.org/wiki/Euler%27s_totient_function
+[6] "Perfect totient number", Wikipedia,
+     https://en.wikipedia.org/wiki/Perfect_totient_number
+
+=end comment
+#==============================================================================
+
+my UInt constant $TARGET = 20;
+my Bool constant $TIME   = False;
+
+#------------------------------------------------------------------------------
+BEGIN
+#------------------------------------------------------------------------------
+{
+    "\nChallenge 175, Task #2: Perfect Totient Numbers (Raku)\n".put;
+}
+
+#==============================================================================
+sub MAIN()
+#==============================================================================
+{
+    my Int $t0 = time if $TIME;
+
+    "The first $TARGET Perfect Totient Numbers:\n\n3".print;
+
+    my UInt $count = 1;
+
+    loop (my UInt $n = 5; $count < $TARGET; $n += 2)
+    {
+        if (iterated-totient-sum( $n ) == $n)
+        {
+            ", $n".print;
+            ++$count;
+        }
+    }
+
+    put();
+
+    "\n%d seconds\n".printf: time - $t0 if $TIME;
+}
+
+#------------------------------------------------------------------------------
+sub iterated-totient-sum( UInt:D $n where { $n > 1 } --> UInt:D )
+#------------------------------------------------------------------------------
+{
+    my UInt $i   = $n;
+    my UInt $sum = 0;
+
+    while $i > 2
+    {
+        $i    = euler-phi( $i );
+        $sum += $i;
+    }
+
+    return ++$sum;      # euler-phi(2) = 1
+}
+
+#------------------------------------------------------------------------------
+sub euler-phi( UInt:D $n where { $n > 1 } --> UInt:D )
+#------------------------------------------------------------------------------
+{
+    # phi(n) = n * Product_{distinct primes p dividing n} (1 - 1/p)
+
+    my UInt @prime-factors = prime-factors( $n ).unique;
+    my Rat  $phi           = $n * [*] @prime-factors.map: { 1 - (1 / $_) };
+
+    return $phi.Int;
+}
+
+#------------------------------------------------------------------------------
+sub prime-factors( UInt:D $n where { $n > 1 } --> Array:D[UInt:D] )
+#------------------------------------------------------------------------------
+{
+    my UInt @prime-factors;
+
+    if $n.is-prime
+    {
+        @prime-factors.push: $n;
+    }
+    else
+    {
+        for 2, 3, 5, 7 ... * -> UInt $p
+        {
+            if $p.is-prime && $n %% $p
+            {
+                @prime-factors.push: $p, |prime-factors( ($n / $p).Int );
+                last;
+            }
+        }
+    }
+
+    return @prime-factors;
+}
+
+#------------------------------------------------------------------------------
+sub USAGE()
+#------------------------------------------------------------------------------
+{
+    my Str $usage = $*USAGE;
+
+    $usage ~~ s:g/ ($*PROGRAM-NAME) /raku $0/;
+
+    $usage.put;
+}
+
+###############################################################################
diff --git a/challenge-175/mohammad-anwar/java/theweeklychallenge/FirstPerfectTotient.java b/challenge-175/mohammad-anwar/java/theweeklychallenge/FirstPerfectTotient.java
new file mode 100644
index 0000000000..2c8027e28c
--- /dev/null
+++ b/challenge-175/mohammad-anwar/java/theweeklychallenge/FirstPerfectTotient.java
@@ -0,0 +1,81 @@
+package theweeklychallenge;
+
+/*
+
+Week 175:
+
+    https://theweeklychallenge.org/blog/perl-weekly-challenge-175
+
+Task #2: Perfect Totient Numbers
+
+    Write a script to generate first 20 Perfect Totient Numbers.
+
+Compile and Run:
+
+    mohammad-anwar/java$ javac theweeklychallenge/FirstPerfectTotient.java
+    mohammad-anwar/java$ java  theweeklychallenge.FirstPerfectTotient
+
+*/
+
+import java.util.Arrays;
+import java.util.ArrayList;
+import junit.framework.TestCase;
+import static junit.framework.Assert.*;
+
+public class FirstPerfectTotient extends TestCase {
+
+    public static void main(String[] args) {
+        junit.textui.TestRunner.run(
+            theweeklychallenge.FirstPerfectTotient.class);
+    }
+
+    public void testFirstPerfectTotient() {
+        Integer[] got = firstPerfectTotient(20);
+        Integer[] exp = {
+            3, 9, 15, 27, 39, 81, 111, 183, 243,
+            255, 327, 363, 471, 729, 2187, 2199,
+            3063, 4359, 4375, 5571
+        };
+
+        assertEquals(Arrays.toString(exp), Arrays.toString(got));
+    }
+
+    public static int gcd(int m, int n) {
+        return n == 0 ? m : gcd(n, m % n);
+    }
+
+    public static boolean isCoprime(int m, int n) {
+        return gcd(m, n) == 1;
+    }
+
+    public static boolean isPerfectTotient(int n) {
+        int i = n;
+        int s = 0;
+        while (i >= 1) {
+            ArrayList<Integer> coprimes = new ArrayList<Integer>();
+            for (int j = 1; j < i; j++) {
+                if (isCoprime(j, i)) {
+                    coprimes.add(j);
+                }
+            }
+            i = coprimes.size();
+            s = s + i;
+        }
+
+        return n == s;
+    }
+
+    public static Integer[] firstPerfectTotient(int n) {
+        ArrayList<Integer> fpt = new ArrayList<Integer>();
+
+        int i  = 1;
+        while (fpt.size() < n) {
+            if (isPerfectTotient(i)) {
+                fpt.add(i);
+            }
+            i++;
+        }
+
+        return fpt.toArray(new Integer[fpt.size()]);
+    }
+}
diff --git a/challenge-175/mohammad-anwar/perl/ch-2.pl b/challenge-175/mohammad-anwar/perl/ch-2.pl
new file mode 100644
index 0000000000..47d464ad34
--- /dev/null
+++ b/challenge-175/mohammad-anwar/perl/ch-2.pl
@@ -0,0 +1,68 @@
+#!/usr/bin/perl
+
+=head1
+
+Week 175:
+
+    https://theweeklychallenge.org/blog/perl-weekly-challenge-175
+
+Task #2: Perfect Totient Numbers
+
+    Write a script to generate first 20 Perfect Totient Numbers.
+
+=cut
+
+use v5.36;
+use Test2::V0;
+
+is [
+     3, 9, 15, 27, 39, 81, 111, 183, 243,
+     255, 327, 363, 471, 729, 2187, 2199,
+     3063, 4359, 4375, 5571
+   ], first_perfect_totient(20);
+
+done_testing;
+
+#
+#
+# METHODS
+
+sub is_coprime($a, $b) {
+    if ($a > $b) {
+        ($a, $b) = ($b, $a);
+    }
+    while ($a) {
+        ($a, $b) = ($b % $a, $a);
+    }
+    return $b == 1;
+}
+
+#
+# Simply coded as shown in the example in the wiki page:
+# https://en.wikipedia.org/wiki/Perfect_totient_number
+
+sub is_perfect_totient($n) {
+    my $i = $n;
+    my $s = 0;
+    while ($i >= 1) {
+        my @coprimes = ();
+        foreach (1 .. $i-1) {
+            push @coprimes, $_ if is_coprime $_, $i;
+        }
+        $i = @coprimes;
+        $s = $s + $i;
+    }
+
+    return $n == $s;
+}
+
+sub first_perfect_totient($n) {
+    my @pt = ();
+    my $i  = 1;
+    while (@pt < $n) {
+        push @pt, $i if is_perfect_totient $i;
+        $i++;
+    }
+
+    return \@pt;
+}
diff --git a/challenge-175/mohammad-anwar/python/ch-2.py b/challenge-175/mohammad-anwar/python/ch-2.py
new file mode 100644
index 0000000000..70ff32d7e2
--- /dev/null
+++ b/challenge-175/mohammad-anwar/python/ch-2.py
@@ -0,0 +1,63 @@
+#!/usr/bin/python3
+
+'''
+
+Week 175:
+
+    https://theweeklychallenge.org/blog/perl-weekly-challenge-175
+
+Task #2: Perfect Totient Numbers
+
+    Write a script to generate first 20 Perfect Totient Numbers.
+
+'''
+
+import math
+import unittest
+
+def isCoprime(a, b) -> bool:
+    return math.gcd(a, b) == 1
+
+#
+# Simply coded as shown in the example in the wiki page:
+# https://en.wikipedia.org/wiki/Perfect_totient_number
+
+def isPerfectTotient(n) -> bool:
+    i = n
+    s = 0
+    while i >= 1:
+        coprimes = []
+        for j in range(1, i):
+            if isCoprime(i, j):
+                coprimes.append(j)
+
+        i = len(coprimes)
+        s = s + i
+
+    return n == s
+
+def firstPerfectTotient(n):
+    pt = []
+    i  = 1
+    while (len(pt) < n):
+        if isPerfectTotient(i):
+            pt.append(i)
+        i = i + 1
+
+    return pt
+
+#
+#
+# Unit test class
+
+class TestPerfectTotient(unittest.TestCase):
+    def test_firstPerfectTotient(self):
+        exp = [
+            3, 9, 15, 27, 39, 81, 111, 183, 243,
+            255, 327, 363, 471, 729, 2187, 2199,
+            3063, 4359, 4375, 5571
+        ]
+        got = firstPerfectTotient(20)
+        self.assertEqual(exp, got)
+
+unittest.main()
diff --git a/challenge-175/mohammad-anwar/raku/ch-2.raku b/challenge-175/mohammad-anwar/raku/ch-2.raku
new file mode 100644
index 0000000000..58917a5d10
--- /dev/null
+++ b/challenge-175/mohammad-anwar/raku/ch-2.raku
@@ -0,0 +1,61 @@
+#!/usr/bin/env raku
+
+=begin pod
+
+Week 175:
+
+    https://theweeklychallenge.org/blog/perl-weekly-challenge-174
+
+Task #2: Perfect Totient Numbers
+
+    Write a script to generate first 20 Perfect Totient Numbers.
+
+=end pod
+
+use Test;
+
+is [
+     3, 9, 15, 27, 39, 81, 111, 183, 243,
+     255, 327, 363, 471, 729, 2187, 2199,
+     3063, 4359, 4375, 5571
+   ], first-perfect-totient(20);
+
+done-testing;
+
+#
+#
+# METHODS
+
+sub is-coprime(Int $a, Int $b --> Bool) {
+    return ($a gcd $b) == 1;
+}
+
+#
+# Simply coded as shown in the example in the wiki page:
+# https://en.wikipedia.org/wiki/Perfect_totient_number
+
+sub is-perfect-totient(Int $n --> Bool) {
+    my Int $i = $n;
+    my Int $s = 0;
+    while $i >= 1 {
+        my Int @coprimes = ();
+        for 1..^$i {
+            @coprimes.push: $_ if is-coprime $_, $i;
+        }
+        $i = @coprimes.elems;
+        $s = $s + $i;
+    }
+
+    return $n == $s;
+}
+
+sub first-perfect-totient(Int $n --> Array[Int]) {
+    my Int @pt = ();
+    my Int $i  = 1;
+    while @pt.elems < $n {
+        @pt.push: $i if is-perfect-totient $i;
+        $i++;
+    }
+
+    return @pt;
+}
diff --git a/challenge-175/mohammad-anwar/swift/ch-2.swift b/challenge-175/mohammad-anwar/swift/ch-2.swift
new file mode 100644
index 0000000000..32169f28b0
--- /dev/null
+++ b/challenge-175/mohammad-anwar/swift/ch-2.swift
@@ -0,0 +1,91 @@
+import Foundation
+
+/*
+
+Week 175:
+
+    https://theweeklychallenge.org/blog/perl-weekly-challenge-175
+
+Task #2: Perfect Totient Numbers
+
+    Write a script to generate first 20 Perfect Totient Numbers.
+
+ACTION:
+
+    $ swift ch-2.swift 20
+
+*/
+
+enum ParamError: Error {
+    case missingNumber
+    case invalidNumber
+}
+
+do {
+    let paramCount:Int = Int(CommandLine.argc)
+
+    if paramCount <= 1 {
+        throw ParamError.missingNumber
+    }
+
+    let num:Int = Int(CommandLine.arguments[1])!
+
+    if num >= 1 {
+        var i:Int = 0
+        var j:Int = 1
+        while i < num {
+            if isPerfectTotient(j) {
+                print(j)
+                i = i + 1
+            }
+            j = j + 1
+        }
+    }
+    else {
+        throw ParamError.invalidNumber
+    }
+}
+catch ParamError.missingNumber {
+    print("Missing number.")
+}
+catch ParamError.invalidNumber {
+    print("Invalid number.")
+}
+catch let error {
+    print(error)
+}
+
+//
+//
+// Functions
+
+func isCoprime(_ m: Int, _ n: Int) -> Bool {
+    var a: Int = 0
+    var b: Int = max(m, n)
+    var r: Int = min(m, n)
+
+    while r != 0 {
+        a = b
+        b = r
+        r = a % b
+    }
+
+    return b == 1
+}
+
+func isPerfectTotient(_ n:Int) -> Bool {
+    var i: Int = n
+    var s: Int = 0
+    while i >= 1 {
+        var coprimes:[Int] = []
+        for j in 1..<i {
+            if isCoprime(j, i) {
+                coprimes.append(j)
+            }
+        }
+        i = coprimes.count
+        s = s + i
+    }
+
+    return n == s
+}
diff --git a/challenge-175/pokgopun/go/ch-2.go b/challenge-175/pokgopun/go/ch-2.go
index 51106c56a2..a94463d9b3 100644
--- a/challenge-175/pokgopun/go/ch-2.go
+++ b/challenge-175/pokgopun/go/ch-2.go
@@ -12,6 +12,7 @@ Output
 package main
 
 import (
+	"fmt"
 	"io"
 	"os"
 	"strconv"
@@ -21,18 +22,11 @@ import (
 )
 
 func main() {
-	var cntdwn uint = 20
-	p := totient.New(cntdwn)
+	var count, start uint64 = 20, 3
+	fmt.Sscanf(strings.Join(os.Args[1:], " "), "%d %d", &count, &start)
 	var b strings.Builder
-	for i := uint(3); i < 200_000; i += 2 {
-		if p.IsPerfect(i) {
-			b.WriteString(", " + strconv.FormatUint(uint64(i), 10))
-			//fmt.Println(i)