#! /usr/bin/perl

use strict;
use warnings;

 my $str1='It is a guide to action which ensures that the military alw
+ays obey the commands of the party.'; chomp($str1);

my $str2='It is a guide to action that ensures that the military will 
+forever heed Party commands is a guide.'; chomp($str2);



my @arr1=split(/\s+/, $str1);

my $n_occur_in_str1=0;

my $n_occur_in_str2=0;

print "-"x60,"\n";
print "nth Match\tNo of occurence\t\tMatched Pattern\n";

print "-"x60,"\n";



for(my $i=0; $i<$#arr1;$i++) {

       my  $t1="$arr1[$i] $arr1[$i+1] $arr1[$i+2]";

        my  @pattern_word_count=split(/\s/, $t1);

        my $space_count=@pattern_word_count;

        if($space_count == 3) {

                if($str2=~/$t1/) {

                     my   $occurence=`echo $str2 | grep -o '$t1' |wc -
+l`; chomp($occurence);

 print $i+1,"\t\t",$occurence,"\t\t\t$t1\n";

                        $n_occur_in_str2+=$occurence;

                        $n_occur_in_str1++;

                }

        }

}



print "\n\nTotal no of occurence in str1 : $n_occur_in_str1\n";

print "\n\nTotal no of occurence in str2 : $n_occur_in_str2\n";
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in the above code i used an array to store the splitted words from sentence and then use each words for further processing

Here, the problem is when i have repeated words, unwantedly i do computation for same words. so to avoid tat i have been advised to store the words in a hash rather than an array.

But, i m not clear how i can do that