Lab Assignment 07

Collaboration Policy

The pre-lab requirement must be completed and submitted individually.

The remainder of the lab activity should be completed working in pairs. One person should submit the result, making sure that both partners' names are clearly identified in that submission.

Please make sure you adhere to the policies on academic integrity in this regard.

Pre-Lab Requirement

Read the complete problem description and then determine what the expected output should be if given the following input:

Phone List

Given a list of phone numbers, determine if it is consistent in the sense that no number is the prefix of another. Let's say the phone catalogue listed these numbers:

• Emergency 911
• Alice 97 625 999
• Bob 91 12 54 26

Input: The first line of input gives a single integer, 1≤t<40, the number of test cases. Each test case starts with n, the number of phone numbers, on a separate line, 1<n<10000. Then follows n lines with one unique phone number on each line. A phone number is a sequence of at most ten digits.

Output: For each test case, output "YES" if hte list is consistent, or "NO" otherwise.

Hints

Although this problem is about "numbers", you should store all of these as strings.

Then, the key to efficiency for this problem is to first sort the list of strings, and then you can determine consistency by checking whether any entry is a prefix of the one immediately following it.

Useful documentation:

• STL string class

• Sorting can be done with sort function from the <algorithm> library, for arrays and vectors, or the sort method of the list class.

  Syntax for sorting array A of length n is: sort(A, A+n).

  Syntax for sorting vector V: sort(V.begin(), V.end()).

  Syntax for sorting list L: L.sort().