Data structure to handle the requirement of following use case

Question

All the records in a database is saved in (key, value) pair formats.Records can always be retrieved by specifying key value. Data structure needs to be developed to handle follo

Answer 1

I am assuming you keys are at most d digits long (in decimal).

How about a normal hashtable and an additional 10*d two dimensional array (let's call it A) of sets. A[i][j] is the set of keys which have digit i in the jth position. The sets can support O(1) insert/delete if implemented themselves as hashtables.