[012#2]

1 files changed, 35 insertions, 0 deletions

diff --git a/012/ch2.pl b/012/ch2.pl
new file mode 100755
index 0000000..6c12861
--- /dev/null
+++ b/012/ch2.pl
@@ -0,0 +1,35 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+sub commonPath {
+    # Normalize paths (merge multiple "/"s into a single one)
+    map s|/+|/|g, @_;
+
+    # This array stores the common path components so far
+    my @common = split m|/|, shift, -1;
+
+    # Iterate over arguments (paths) and update @common accordingly
+    foreach my $path (@_) {
+        my @current = split m|/|, $path, -1;
+
+        # Cut @common if longer than the current one
+        @common = @common[0 .. $#current] if $#current < $#common;
+
+        # Cut @common to keep only the matching components
+        foreach my $i (0 .. $#common) {
+            if ($common[$i] ne $current[$i]) {
+                @common = @common[0 .. $i-1];
+                last;
+            }
+        }
+    }
+
+    # Corner case: @common == ('') means root
+    return @common == 1 && $common[0] eq ''
+        ? "/"
+        : join "/", @common;
+}
+
+print commonPath(@ARGV), "\n";