comment on

Just that in 2 of the test cases, it gets timed out.

I see the following inefficiencies, which I already touched upon:

Reading the entire input into memory is unnecessary, it is enough to process the input line-by-line.
As Corion already pointed out, you're doing what appears to be unnecessary work on the input. Unless there are other requirements for the input format that you haven't told us about?
When looking up a phone number, you're searching the entire @data array twice, first with grep, then with for ( my $m = 0 ; $m <= $len1 ; $m++ ). Also, in the grep you're using a regular expression, which appears unnecessary and takes up CPU cycles since later on you're just doing an exact comparison with if ( $data[$m] eq $N[$i] ).
Using grep is inefficient for finding a single array element, as it searches the entire array. There would be the alternative first from the core module List::Util, which returns the first match, but if all you need is exact matches, even better would be hash lookups.

Hope this helps,
-- Hauke D

In reply to Re^3: Perl program to look into the phone directory ... by haukex
in thread Perl program to look into the phone directory and in case of a match, print the name along with the number by dk27

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