#!/usr/bin/perl -w

package Tnode;

sub new {
   my( $class, $word, $count ) = @_;
   my $self = {};
   $self->{word}  = $word;
   $self->{count} = $count;
   $self->{left}  = undef;
   $self->{right} = undef;

   return bless $self, $class;
}

package main;

die unless @ARGV;

my $root = undef;

while(<>) {
   chomp;
   $word = $_;
   $root = tree( $root, $word );
}

treeprint( $root );

sub tree {
   my( $node, $word ) = @_;

   if( ! $node ) {
      $node = Tnode->new( $word, 1 );
      $node->{left} = undef;
      $node->{right} = undef;
   } elsif( $node->{word} eq $word ) {
      $node->{count}++;
   } elsif( $word lt $node->{word} ) {
      $node->{left} = tree( $node->{left}, $word );
   } else {
      $node->{right} = tree( $node->{right}, $word );
   }

   return $node;
}

sub treeprint {
   my( $root ) = shift;

   if( $root ) {
      treeprint( $root->{left} );
      printf( "%4d %s\n", $root->{count}, $root->{word} );
      treeprint( $root->{right} );
   }
}

##</code><code>##

#!/usr/bin/perl -w

use Inline C;

package Tnode;

sub new {
   my( $class, $word, $count ) = @_;
   my $self = {};
   $self->{word}  = $word;
   $self->{count} = $count;
   $self->{left}  = undef;
   $self->{right} = undef;

   return bless $self, $class;
}

package main;

die unless @ARGV;

my $root = undef;

while(<>) {
   chomp;
   $word = $_;
   $root = tree( $root, $word );
}

treeprint( $root );

sub tree {
   my( $node, $word ) = @_;

   if( ! $node ) {
      $node = Tnode->new( $word, 1 );
      $node->{left} = undef;
      $node->{right} = undef;
   } elsif( $node->{word} eq $word ) {
      $node->{count}++;
   } elsif( $word lt $node->{word} ) {
      $node->{left} = tree( $node->{left}, $word );
   } else {
      $node->{right} = tree( $node->{right}, $word );
   }

   return $node;
}
__END__
__C__

void treeprint( SV *root ) {

   HV* hash;
   HE* hash_entry;
   SV* node;
   SV* word;
   SV* count;

   if( !SvROK(root) )
      return;

   hash = (HV*)SvRV(root);

   node = get_child( hash, "left" );
   if( node != NULL ) {
      treeprint( node );
   }

   output( hash );

   node = get_child( hash, "right" );
   if( node != NULL ) {
      treeprint( node );
   }
}

SV *get_child( HV *hash, char *key ) {
   int num_keys, i;
   HE *hash_entry;
   SV *sv_key;
   SV *sv_val;

   num_keys = hv_iterinit(hash);
   for (i = 0; i < num_keys; i++) {
      hash_entry = hv_iternext(hash);
      sv_key = hv_iterkeysv(hash_entry);
      sv_val = hv_iterval(hash, hash_entry);
      if( strcmp( SvPV( sv_key, PL_na), key ) == 0 ) {
         return( sv_val );
      }
   }

   sv_val = NULL;
   return sv_val;
}

void output( HV *hash ) {
   int num_keys, i;
   HE *hash_entry;
   SV *sv_key;
   SV *sv_val;
   int count;
   char *word = NULL;

   num_keys = hv_iterinit(hash);
   for(i = 0; i < num_keys; i++) {
      hash_entry = hv_iternext(hash);
      sv_key = hv_iterkeysv(hash_entry);
      sv_val = hv_iterval(hash, hash_entry);
      if( strcmp( SvPV( sv_key, PL_na), "word" ) == 0 ) {
         word = SvPV( sv_val, PL_na);
      }
      if( strcmp( SvPV( sv_key, PL_na), "count" ) == 0 ) {
         count = SvIV( sv_val );
      }
   }

   if( word ) {
      printf( "%4d %s\n", count, word );
   }
}

##</code><code>##

Benchmark: timing 50000 iterations of inline, perl...
   inline: 13 wallclock secs (12.42 usr +  0.00 sys = 12.42 CPU) @ 
      4025.76/s (n=50000)
   perl: 12 wallclock secs (12.27 usr +  0.00 sys = 12.27 CPU) @ 
      4074.98/s (n=50000)