CareerCup

was the questions written on machine, i mean did u wrote runnable code?

@varun .. can you explain the logic here ?

For a small phonebook ,a 2-D matrix would work having name*phone-number entries.
For larger one, use a suffix tree which stores phone number and name alike as strings. This also gives the feature of listing all possible entries for a partial entry.
Other option is to have 2 maps, phone-name and name-map.

U can use sets

Use Perl CPAN implementation of suffix tree's.

Use Perl CPAN implementation of suffix tree's. Code can be written in no time.

trie

Trie but the problem is are you going to edit 2 tries wheneer u add or del an entry in the ph book