https://theweeklychallenge.org/blog/perl-weekly-challenge-331/

2 files changed, 41 insertions, 0 deletions

diff --git a/challenge-331/kjetillll/perl/ch-1.pl b/challenge-331/kjetillll/perl/ch-1.pl
new file mode 100644
index 0000000000..d9e43bfe34
--- /dev/null
+++ b/challenge-331/kjetillll/perl/ch-1.pl
@@ -0,0 +1,5 @@
+sub f{ pop =~ /(\w+)\s*$/; length $1 }
+    
+print f('The Weekly Challenge') == 9 ? "ok\n" : "err\n";
+print f('   Hello   World    ') == 5 ? "ok\n" : "err\n";
+print f("Let's begin the fun")  == 3 ? "ok\n" : "err\n";
diff --git a/challenge-331/kjetillll/perl/ch-2.pl b/challenge-331/kjetillll/perl/ch-2.pl
new file mode 100644
index 0000000000..98d5cd9afc
--- /dev/null
+++ b/challenge-331/kjetillll/perl/ch-2.pl
@@ -0,0 +1,36 @@
+
+sub f {
+    my($a, $b) = @_;
+    $a =~ /^ #match from beginning of string $a
+      (.*)   #substring before first swapped letter
+      (.)    #first swapped letter
+      (.*)   #substring between the two swapped letters
+      (.)    #second swapped letter
+      (.*)   #substring after the second swapped letter
+     $       #match up to end of string $a
+     (??{    #make the regexp engine try and retry different lengths of the three (.*) parts
+             #until the swapped string equals $b. Or it will give up with false as a result.
+       my $trial = "$1$4$3$2$5"; # $a with two letters swapped
+       $trial eq $b   #check if the trial string now equals $b
+       ? ''           #if so, no need to match anything more thus '', and the regex and also f() returns true
+       : '^'          #make this trial fail with the impossible ^ match (beginning of string),
+                      #and if no more trials the regex and also f() returns false
+     }) 
+    /x                # /x ignores regexp whitespace and allows #comments
+}
+
+#sub f{my($a,$b)=@_;$a=~/^(.*)(.)(.*)(.)(.*)$(??{"$1$4$3$2$5"eq$b?'':'^'})/}
+
+print f("fudge", "fduge") ? "ok\n" : "err\n";  # true
+print f("love", "love")   ? "err\n" : "ok\n";  # false
+print f("fodo", "food")   ? "ok\n" : "err\n";  # true
+print f("feed", "feed")   ? "ok\n" : "err\n";  # true
+
+print f("perl", "erlp")   ? "err\n" : "ok\n";  # false
+print f("perl", "prel")   ? "ok\n" : "err\n";  # true
+print f("regexp challenge", "regexp challenge") ? "ok\n" : "err\n";  # true, l and l swapped
+print f("regexp challenge", "regexg challenpe") ? "ok\n" : "err\n";  # true
+print f("challenge", "challegne") ? "ok\n" : "err\n";  # true
+print f("challenge", "challeneg") ? "ok\n" : "err\n";  # true
+print f("challenge", "hcallenge") ? "ok\n" : "err\n";  # true
+print f("challenge", "hcallegne") ? "err\n" : "ok\n";  # false, needs two swaps