Create ch-2a.p6

1 files changed, 20 insertions, 0 deletions

diff --git a/perl6/ch-2a.p6 b/perl6/ch-2a.p6
new file mode 100644
index 0000000000..92f61119e1
--- /dev/null
+++ b/perl6/ch-2a.p6
@@ -0,0 +1,20 @@
+#!/usr/bin/env perl6
+# Find single longest common substring for just 2 cmdline specified strings.
+# This was a first attempt; the low-level approach seems somewhat difficult to generalize to multiple lcs in 2+ strings.
+
+sub MAIN (Str $string1 , Str $string2) {
+
+    my @string1     = $string1.comb;
+    my @string2     = $string2.comb;
+    my ($l1, $l2)   = (@string1.elems, @string2.elems);
+    my ($x,$z)      = (0,0);                                # $x is lcs-index into @string1, $z is length of lcs
+
+    for 0..$l1-1 -> $i {
+        for 0..$l2-1 -> $j {
+            my $k=0; 
+            $k++ while ($i+$k < $l1) && ($j+$k < $l2) && (@string1[$i+$k] eq @string2[$j+$k]);
+            if $k > $z { ($x, $z) = ($i, $k) };
+        }
+    }
+    say "LCS  = { $string1.substr($x, $z) }";
+}