TopCoder problem "HexatridecimalSum" used in SRM 434 (Division I Level Two , Division II Level Three)

Problem Statement

Hexatridecimal notation is base 36 notation. The digits are '0' to '9' (with values 0 to 9) and 'A' to 'Z' (with values 10 to 35).

You are given a String[] numbers, where each element represents a positive integer in hexatridecimal notation. You must select exactly k digits (from the set of all digits - '0' to '9' and 'A' to 'Z') and replace all of their occurrences in all of the numbers with 'Z'. Then, calculate the sum of all the numbers.

Return the maximal possible sum you can get. The return value must be in hexatridecimal format with no leading zeroes.

Definition

Class:	HexatridecimalSum
Method:	maximizeSum
Parameters:	String[], int
Returns:	String
Method signature:	String maximizeSum(String[] numbers, int k)
(be sure your method is public)

Constraints

numbers will contain between 1 and 50 elements, inclusive.

Each element of numbers will contain between 1 and 50 characters, inclusive.

Each element of numbers will contain only characters '0' to '9' and 'A' to 'Z'.

Each element of numbers will not start with '0'.

k will be between 0 and 36, inclusive.

Examples

{"HELLO"}

Returns: "ZZLLO"

It is optimal to change the two most significant digits in the given number.

{"500", "POINTS", "FOR", "THIS", "PROBLEM"}

Returns: "1100TC85"

{"TO", "BE", "OR", "NOT", "TO", "BE"}

Returns: "QNO"

k = 0 means that you're not allowed to change any digits, so the answer is the sum of the given numbers.

{"KEQUALS36"}

Returns: "ZZZZZZZZZ"

k = 36 means that you have to replace all the letters with 'Z'.

{"GOOD", "LUCK", "AND", "HAVE", "FUN"}

Returns: "31YUB"

Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=10266

Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=13696&pm=10266

Writer:

darnley

Testers:

PabloGilberto , Olexiy , ivan_metelsky

Problem categories:

Simple Math, Sorting, String Manipulation