simple-fun-number-2-circle-of-numbers

Simple Fun #2: Circle of Numbers

Consider integer numbers from 0 to n - 1 written down along the circle in such a way that the distance between any two neighbouring numbers is equal (note that 0 and n - 1 are neighbouring, too).

Given n and firstNumber/first_number, find the number which is written in the radially opposite position to firstNumber.

Example

For n = 10 and firstNumber = 2, the output should be

CircleOfNumbers.circleOfNumbers(n, firstNumber) == 7

Input/Output

• [input] integer n

  A positive even integer.

  Constraints: 4 ? n ? 1000.

• [input] integer firstNumber/first_number

  Constraints: 0 ? firstNumber ? n - 1

• [output] an integer