10 files changed, 236 insertions, 0 deletions
diff --git a/challenge-010/feng-chang/README b/challenge-010/feng-chang/README
new file mode 100644
index 0000000000..74e56de3ed
--- /dev/null
+++ b/challenge-010/feng-chang/README
@@ -0,0 +1 @@
+Solutions by Feng Chang.
diff --git a/challenge-010/feng-chang/perl6/ch-1.p6 b/challenge-010/feng-chang/perl6/ch-1.p6
new file mode 100755
index 0000000000..5b928bdb80
--- /dev/null
+++ b/challenge-010/feng-chang/perl6/ch-1.p6
@@ -0,0 +1,33 @@
+#!/bin/env perl6
+
+sub d2r(Int $i where 0 <= * <= 9, Str $c1, Str $c5, Str $c10) returns Str {
+    given ($i) {
+        when (9)         { return $c1 ~ $c10 }
+        when (* ~~ 5..8) { return $c5 ~ $c1 x ($i - 5) }
+        when (4)         { return $c1 ~ $c5 }
+        when (* ~~ 0..3) { return $c1 x $i }
+    }
+}
+
+multi sub MAIN(Str $p where * ~~ /^ <[IVXLCDM]>+ $/) {
+    my %r2a = 'I' => 1, 'V' => 5, 'X' => 10, 'L' => 50, 'C' => 100, 'D' => 500, 'M' => 1000;
+    my @a = $p.comb.map:{ %r2a{ $_ } };
+
+    my $sum = [+] (0 .. (@a.elems - 2)).map:{ @a[$_] < @a[$_ + 1] ?? -@a[$_] !! @a[$_] };
+    $sum += @a[* - 1];
+
+    say $sum;
+}
+
+multi sub MAIN(UInt $p) {
+    my Str $s = 'M' x ($p div 1000);
+    my Int $n = $p mod 1000;
+
+    $s ~= d2r($n div 100, 'C', 'D', 'M');
+    $n %= 100;
+
+    $s ~= d2r($n div 10, 'X', 'L', 'C');
+    $s ~= d2r($n mod 10, 'I', 'V', 'X');
+
+    say $s;
+}
diff --git a/challenge-010/feng-chang/perl6/ch-2.p6 b/challenge-010/feng-chang/perl6/ch-2.p6
new file mode 100755
index 0000000000..7773c07831
--- /dev/null
+++ b/challenge-010/feng-chang/perl6/ch-2.p6
@@ -0,0 +1,37 @@
+#!/bin/env perl6
+
+sub jaro-similarity(Str $s1, Str $s2) returns Num {
+    my Int $s1-len = $s1.chars;
+    my Int $s2-len = $s2.chars;
+    my Int $d      = max($s1-len, $s2-len) div 2 - 1;
+
+    my Int $m   = 0;        # matching characters
+    my Str @as1 = $s1.comb;
+    my Str $ms1 = '';       # string made up of matching characters from s1
+    for 0 .. $s1-len - 1 -> Int $i {
+        if $s2.substr(max(0, $i - $d) .. min($s2-len, $i + $d)).contains(@as1[$i]) {
+            ++$m;
+            $ms1 ~= @as1[$i];
+        }
+    }
+
+    return 0e0 if $m == 0;
+
+    my Str @as2 = $s2.comb;
+    my Str $ms2 = '';       # string made up of matching characters from s2
+    for 0 .. $s2-len - 1 -> Int $i {
+        $ms2 ~= @as2[$i] if $s1.substr(max(0, $i - $d) .. min($s1-len, $i + $d)).contains(@as2[$i]);
+    }
+
+    my Int $nt = 0;
+    for $ms1.comb Z $ms2.comb -> $p {
+        ++$nt if $p[0] eq $p[1];
+    }
+
+    return 1e0 / 3 * ($m / $s1-len + $m / $s2-len + $nt / $m);
+}
+
+sub jaro-winkler-similarity(Str $s1, Str $s2) returns Num {
+}
+
+my $sim-j = jaro-similarity('CRATE', 'TRACE');
diff --git a/challenge-010/feng-chang/perl6/test-ch-1.p6 b/challenge-010/feng-chang/perl6/test-ch-1.p6
new file mode 100755
index 0000000000..316b72ec90
--- /dev/null
+++ b/challenge-010/feng-chang/perl6/test-ch-1.p6
@@ -0,0 +1,29 @@
+#!/bin/env perl6
+
+use Test;
+plan 24;
+
+dec-vs-rom(39, 'XXXIX');
+
+dec-vs-rom(160, 'CLX');
+dec-vs-rom(207, 'CCVII');
+dec-vs-rom(246, 'CCXLVI');
+dec-vs-rom(789, 'DCCLXXXIX');
+
+dec-vs-rom(1009, 'MIX');
+dec-vs-rom(1066, 'MLXVI');
+dec-vs-rom(1776, 'MDCCLXXVI');
+dec-vs-rom(1954, 'MCMLIV');
+dec-vs-rom(2014, 'MMXIV');
+dec-vs-rom(2019, 'MMXIX');
+dec-vs-rom(2421, 'MMCDXXI');
+
+sub dec-vs-rom(Int $n, Str $s) {
+    my $script = './01.p6';
+
+    my $res = run $script, $n, :out;
+    is $res.out.get, $s, "$n => $s";
+
+    $res = run $script, $s, :out;
+    is $res.out.get, $n, "$s => $n";
+}
diff --git a/challenge-012/feng-chang/perl5/ch-1.pl b/challenge-012/feng-chang/perl5/ch-1.pl
new file mode 100755
index 0000000000..21129a546b
--- /dev/null
+++ b/challenge-012/feng-chang/perl5/ch-1.pl
@@ -0,0 +1,72 @@
+#!/bin/env perl
+
+use Modern::Perl;
+use List::Util qw(min max);
+use POSIX;
+
+my @primes = (2, 3);
+
+sub more_primes {
+    my $to   = shift;
+    my $from = $primes[-1] + 1;
+    my $P;
+
+    do {
+        $P = $primes[-1];
+        my @a = ($P + 1) .. min($to, $P * $P);
+
+        for my $p (@primes) {
+            for (my $i = ceil($from / $p) * $p - $from; $i <= $to; $i += $p) {
+                $a[$i] = 0;
+            }
+        }
+
+        for my $i (@a) {
+            push(@primes, $i) if $i;
+        }
+    } while ($P * $P < $to);
+}
+
+sub is_prime {
+    my $n = shift;
+
+    my $e = int(sqrt($n));
+    more_primes($e) if $e > $primes[-1];
+
+    for my $p (@primes) {
+        last if $p > $e;
+        return 0 if $n % $p == 0;
+    }
+
+    return 1;
+}
+
+sub get_prime {
+    my $idx = shift;
+    return $primes[$idx] if $idx + 1 <= @primes;
+
+    do {
+        my $n = $primes[-1];
+        more_primes($n * $n);
+    } while ($idx + 1 > @primes);
+
+    return $primes[$idx];
+}
+
+if (@ARGV) {
+    my $n = $ARGV[0];
+    say "$n is ", is_prime($n) ? '' : 'not ', 'prime';
+    exit 0;
+}
+
+my $prod = 1;
+my $i    = 0;
+while (1) {
+    $prod *= get_prime($i);
+    print $primes[$i], ' ';
+    last unless is_prime($prod + 1);
+
+    ++$i;
+}
+
+say $prod + 1;
diff --git a/challenge-012/feng-chang/perl5/ch-2.pl b/challenge-012/feng-chang/perl5/ch-2.pl
new file mode 100755
index 0000000000..c3c26e5f79
--- /dev/null
+++ b/challenge-012/feng-chang/perl5/ch-2.pl
@@ -0,0 +1,27 @@
+#!/bin/env perl
+
+use Modern::Perl;
+use List::Util qw(reduce);
+
+sub common_prefix {
+    my ($a, $b) = @_;
+    my @a = split //, $a;
+    my @b = split //, $b;
+
+    my $r = '';
+    my $i = 0;
+    while ($a[$i] && $b[$i] && $a[$i] eq $b[$i]) {
+        $r .= $a[$i++];
+    }
+
+    return $r;
+}
+
+chomp(my @paths = <>);
+my $common_path = reduce { common_prefix($a, $b) } @paths;
+
+my @c = split //, $common_path;
+pop @c while $c[-1] ne '/';
+pop @c if @c > 1;
+
+say 'common directory path: ', join('', @c);
diff --git a/challenge-012/feng-chang/perl5/paths.txt b/challenge-012/feng-chang/perl5/paths.txt
new file mode 100644
index 0000000000..1427e2dbc8
--- /dev/null
+++ b/challenge-012/feng-chang/perl5/paths.txt
@@ -0,0 +1,4 @@
+/a/b/c/d
+/a/b/cd
+/a/b/cc
+/a/b/c/d/e
diff --git a/challenge-012/feng-chang/perl6/ch-1.p6 b/challenge-012/feng-chang/perl6/ch-1.p6
new file mode 100755
index 0000000000..5e58b20b50
--- /dev/null
+++ b/challenge-012/feng-chang/perl6/ch-1.p6
@@ -0,0 +1,12 @@
+#!/bin/env perl6
+
+my $euc = (^∞).grep: *.is-prime;
+
+my $prod = 1;
+for 0 .. ∞ -> Int $i {
+    $prod *= $euc[$i];
+    print $euc[$i], ' ';
+    last unless ($prod + 1).is-prime;
+
+    LAST { say $prod + 1 }
+}
diff --git a/challenge-012/feng-chang/perl6/ch-2.p6 b/challenge-012/feng-chang/perl6/ch-2.p6
new file mode 100755
index 0000000000..1ea095468d
--- /dev/null
+++ b/challenge-012/feng-chang/perl6/ch-2.p6
@@ -0,0 +1,17 @@
+#!/bin/env perl6
+
+sub common_prefix(Str $a, Str $b) {
+    my @a = $a.comb;
+    my @b = $b.comb;
+
+    for 0..∞ -> $i {
+        last unless @a[$i].defined && @b[$i].defined && @a[$i] eq @b[$i];
+        LAST { return @a[0 .. $i - 1].join }
+    }
+}
+
+my @c = ([[&common_prefix]] 'paths.txt'.IO.lines).comb;
+@c.pop while @c[* - 1] ne '/';
+@c.pop if @c.elems > 1;
+
+say 'common directory path: ', @c.join;
diff --git a/challenge-012/feng-chang/perl6/paths.txt b/challenge-012/feng-chang/perl6/paths.txt
new file mode 100644
index 0000000000..1427e2dbc8
--- /dev/null
+++ b/challenge-012/feng-chang/perl6/paths.txt
@@ -0,0 +1,4 @@
+/a/b/c/d
+/a/b/cd
+/a/b/cc
+/a/b/c/d/e