part 2

2018/02/sol2.pl

@@ -0,0 +1,39 @@
+use 5.20.0;
+use warnings;
+
+my @items = <>;
+
+use List::AllUtils qw/ pairwise /;
+
+use experimental qw/
+    signatures
+    postderef 
+    current_sub
+/;
+
+while( my $next = shift @items ) {
+    my $match = find([ split '', $next], @items) or next;
+    say $match;
+    last;
+}
+
+sub find( $next, @items ) {
+    my $contender = splice @_, 1, 1 or return;
+    $contender = [ split '', $contender ];
+
+    my $diff = 0;
+    my $r = '';
+
+    for my $i ( 0..$next->@* ) {
+        if ( $next->[$i] eq $contender->[$i] ) {
+            $r .= $next->[$i];
+        }
+        else {
+            last if $diff++;
+        }
+    }
+
+    return $r if $diff == 1;
+
+    goto __SUB__;
+}