# HG changeset patch
# User Eris Caffee <discordia@eldalin.com>
# Date 1430845336 18000
# Node ID e1578d3eee360b80fed2fb5113befea56d305b9a
# Parent  9e16e99a4a10840effaa3f81df3c0e0e8cf3dce1
Added is_palindrome tests.

diff -r 9e16e99a4a10 -r e1578d3eee36 palindrome/is_palindrome.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/palindrome/is_palindrome.cpp	Tue May 05 12:02:16 2015 -0500
@@ -0,0 +1,34 @@
+#include <cstring>
+#include <cctype>
+#include <iostream>
+#include <string>
+
+bool is_palindrome( const char *s ) {
+    const char * first = s;
+    const char * last = s + strlen(s) - 1;
+    while ( first < last ) {
+        while ( ! isalpha( *first ) && *first != 0 )
+            first++;
+        while ( ! isalpha( *last ) && last >= s )
+            last--;
+        if ( toupper( *first ) != toupper( *last ) ) {
+            return false;
+            }
+        first++;
+        last--;
+        }
+    return true;
+    }
+
+bool is_palindrome( std::string s ) {
+    return is_palindrome( s.c_str() );
+    }
+
+int main ( int argc, char **argv ) {
+    for ( int i = 1; i < argc; ++i ) {
+        std::string s(argv[1]);
+        std::cout << is_palindrome( s ) << std::endl;
+        }
+
+    return 0;
+    }
diff -r 9e16e99a4a10 -r e1578d3eee36 palindrome/is_palindrome.pl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/palindrome/is_palindrome.pl	Tue May 05 12:02:16 2015 -0500
@@ -0,0 +1,31 @@
+use strict;
+use warnings;
+
+# This implements the same algorithm as the C++ version, but it has to first
+# split the string into an array, and therefore uses O(N) extra space.
+
+sub is_palindrome {
+    my $s = shift;
+    my @chars = split( //, $s );
+    my $first = 0;
+    my $last = scalar( @chars ) - 1;
+    while ( $first < $last ) {
+        while ( ( $chars[$first] !~ /^[a-zA-Z]$/  ) and ( $first < scalar( @chars ) ) ) {
+            $first++;
+        }
+        while ( ( $chars[$last] !~ /^[a-zA-Z]$/  ) and ( $last > 0 ) ) {
+            $last--;
+        }
+
+        if ( lc($chars[$first]) ne lc($chars[$last]) ) {
+            return 0;
+        }
+        $first++;
+        $last--;
+    }
+    return 1;
+}
+
+for ( my $i = 0; $i < scalar( @ARGV ) ; $i++ ) {
+    print is_palindrome( $ARGV[$i] ) . "\n";
+}