1 use strict;

2 use warnings;

3

4 # This implements the same algorithm as the C++ version, but it has to first

5 # split the string into an array, and therefore uses O(N) extra space.

6

7 sub is_palindrome {

8 my $s = shift;

9 my @chars = split( //, $s );

10 my $first = 0;

11 my $last = scalar( @chars ) - 1;

12 while ( $first < $last ) {

13 while ( ( $chars[$first] !~ /^[a-zA-Z]$/ ) and ( $first < scalar( @chars ) ) ) {

14 $first++;

15 }

16 while ( ( $chars[$last] !~ /^[a-zA-Z]$/ ) and ( $last > 0 ) ) {

17 $last--;

18 }

19

20 if ( lc($chars[$first]) ne lc($chars[$last]) ) {

21 return 0;

22 }

23 $first++;

24 $last--;

25 }

26 return 1;

27 }

28

29 for ( my $i = 0; $i < scalar( @ARGV ) ; $i++ ) {

30 print is_palindrome( $ARGV[$i] ) . "\n";

31 }