Re^3: Perl program to look into the phone directory and in case of a match, print the name along with the number

I'm not sure whether the optimization would contribute much to the overall speedup, but the following two lines do much needless work:

    $s =~ s/\s+/=/g;
    my @v = split( /[\[\],]/, $s ); #create an array from string $s
# assign hash value pairs and insert '=' between them to create phoneb
+ook 
    my %hash = map { split( /=/, $_, $x + 1 ) } @v; 
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Why do you convert all whitespace in $s to = and then split on = again? What use is @v?

Also, the fasted way to do general lookups in Perl is to use a hash. In your case, the fastest data structure to look up the name from a number would be a hash that maps each number to a name:

my %reverse_phonebook = (
    123 => 'jack',
    456 => 'jill',
    ...
);
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Building this data structure allows for quick repeated lookups of names if all you have is the number.

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