week 115

4 files changed, 122 insertions, 5 deletions

diff --git a/challenge-114/cheok-yin-fung/perl/ch-1.pl b/challenge-114/cheok-yin-fung/perl/ch-1.pl
index d061baf685..0959087a47 100644
--- a/challenge-114/cheok-yin-fung/perl/ch-1.pl
+++ b/challenge-114/cheok-yin-fung/perl/ch-1.pl
@@ -19,10 +19,10 @@ sub higher_pal {
         return (10**length $n)+1;
     }
 
-    my $suff = substr($n, 0, ((length $n) + 1)/2);
-    my $p = pal_from_half( $suff, (length $n) % 2 );
+    my $_prefix = substr($n, 0, ((length $n) + 1)/2);
+    my $p = pal_from_half( $_prefixf, (length $n) % 2 );
     if ($n >= $p) {
-        return pal_from_half( $suff+1, (length $n) % 2 );
+        return pal_from_half( $_prefixf+1, (length $n) % 2 );
     } 
     else {
         return $p;
@@ -31,9 +31,9 @@ sub higher_pal {
 
 sub pal_from_half {
     my $s = $_[0];
-    my $suf = substr( $s  , 0 , (length $s) - $_[1] );
+    my $prefix = substr( $s  , 0 , (length $s) - $_[1] );
     my $mid = $_[1] ? substr($s, -1, 1) : "";
-    my $new = join "", $suf, $mid, reverse (split //, $suf);
+    my $new = join "", $prefix, $mid, reverse (split //, $prefix);
     return $new;
 }
 
diff --git a/challenge-115/cheok-yin-fung/blog.txt b/challenge-115/cheok-yin-fung/blog.txt
new file mode 100644
index 0000000000..3cc4d8bb0f
--- /dev/null
+++ b/challenge-115/cheok-yin-fung/blog.txt
@@ -0,0 +1 @@
+file:///home/e78783/E7-87-83.github.io/coding/challenge_115.html
diff --git a/challenge-115/cheok-yin-fung/perl/ch-1.pl b/challenge-115/cheok-yin-fung/perl/ch-1.pl
new file mode 100644
index 0000000000..299aee2eaf
--- /dev/null
+++ b/challenge-115/cheok-yin-fung/perl/ch-1.pl
@@ -0,0 +1,80 @@
+#!/usr/bin/perl
+# The Weekly Challenge 115
+# Task 1 String Chain
+# Usage: ch-1.pl @S
+use strict;
+use warnings;
+
+my @S = @ARGV;
+@S = ("ade", "cbd", "fgh") if !@S;
+
+
+
+if (consistent_degrees(@S) && is_connected(@S)) {
+    print 1;
+}
+else {
+    print 0;
+}
+print "\n";
+
+
+
+sub consistent_degrees {
+    my @edges = @_;
+    my %i_vertex;
+    my %o_vertex;
+    for my $str (@edges) {
+        my $head = substr $str, 0, 1;
+        my $tail = substr $str, -1, 1;
+        push $i_vertex{$tail}->@*, $head;
+        push $o_vertex{$head}->@*, $tail;
+    }
+
+    for my $letter (keys %i_vertex) {
+        if (!$o_vertex{$letter}) {
+            return 0;
+        }
+        if (scalar @{$i_vertex{$letter}}
+              != scalar @{$o_vertex{$letter}}) {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+
+sub is_connected {
+    my @edges = @_;
+    my %collected;
+    my %vertex_neigh;
+    for my $str (@edges) {
+        my $head = substr $str, 0, 1;
+        my $tail = substr $str, -1, 1;
+        $collected{$head} = -1;
+        $collected{$tail} = -1;
+        push $vertex_neigh{$head}->@*, $tail;
+        push $vertex_neigh{$tail}->@*, $head;
+    }
+    # depth-first search
+    my @stack = substr($edges[0], 0, 1);
+    while (scalar @stack != 0) {
+        my $cur = pop @stack;
+        if ($collected{$cur} == 1) {
+            next;
+        }
+        else {
+            for my $neigh ($vertex_neigh{$cur}->@*) {
+                push @stack, $neigh if $collected{$neigh} == -1;
+            }
+            $collected{$cur} = 1;
+        }
+    }
+    #check connectedness
+    for my $letter (keys %collected) {
+        if ($collected{$letter} == -1) {
+            return 0;
+        }
+    }
+    return 1;
+}
diff --git a/challenge-115/cheok-yin-fung/perl/ch-2.pl b/challenge-115/cheok-yin-fung/perl/ch-2.pl
new file mode 100644
index 0000000000..66d442e9a9
--- /dev/null
+++ b/challenge-115/cheok-yin-fung/perl/ch-2.pl
@@ -0,0 +1,36 @@
+#!/usr/bin/perl
+# The Weekly Challenge 115
+# Task 2 Largest Multiple
+# Usage: ch-2.pl [digits from 0-9]
+use strict;
+use warnings;
+
+my @digits = @ARGV;
+
+if (!@digits) {@digits = (1,0,4,8,5,7,6);} 
+
+for (@digits) {
+    die "Please input digits seperated by spaces.\n", 
+        "Usage: ch-2.pl [digits from 0-9]\n"
+        unless $_ =~ /^[0-9]$/;
+}
+
+
+@digits = sort {$b <=> $a} @digits;
+
+my $least_sig_fig = -1;
+for (reverse 0..$#digits) {
+    if ($digits[$_] =~ /[02468]/ ) {
+        $least_sig_fig = splice(@digits, $_, 1);
+        push @digits, $least_sig_fig;
+        last;
+    }
+}
+if ($least_sig_fig == -1) {
+    print "NULL", "\n";
+}
+else {
+    print join "", @digits;
+    print "\n";
+}
+