TopCoder SRM 148, DIV II, MNS

Problem Statement

9 numbers need to be arranged in a magic number square. A magic number square is a square of numbers that is arranged such that every row and column has the same sum. For example:

1 2 3
3 2 1
2 2 2
Create a class MNS containing a method combos which takes as an argument a int[] numbers and returns the number of distinct ways those numbers can be arranged in a magic number square. Two magic number squares are distinct if they differ in value at one or more positions. For example, there is only one magic number square that can be made of 9 instances of the same number.

TopCoder SRM 148, DIV II, DivisorDigits

Problem Statement

Create a class DivDigits containing a method howMany which takes as an argument an int number and returns how many digits in number that number itself is divisible by. Count all occurences of such digits in the number, not just the first. See examples for more information.

TopCoder SRM 148, DIV II, CeyKaps

Problem Statement

The keycaps on a keyboard have been switched around, and the user is now trying to remember what he was trying to type.

Create a class CeyKaps containing the method decipher that takes a String typed, representing the visible message on the screen, and a String[] switched, representing the keycap switches. The method should return the original intended message (what keys the user thought he was pressing).

A keycap can be switched around more than once. For example, if someone switched around 'A' and 'S', then switched around 'S' and 'D', then 'D' would be where 'A' originally was, 'S' where 'D' was, and 'A' where 'S' was.

The elements of switches will be formatted as (quotes added for clarity) "*:*", where the *'s represent the keycaps to be switched. The above example would be represented as: {"A:S","S:D","D:A"}, or alternately as {"S:A","D:S","A:D"} or any other such combination. The order of the keycaps doesn't matter, but the order of the switches does.