circleOfNumbers.R

# Consider integer numbers from 0 to n - 1 written down along the circle in such a way that the distance between any two neighboring numbers is equal (note that 0 and n - 1 are neighboring, too).
# 
# Given n and firstNumber, 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(n, firstNumber) = 7.
# 
# Input/Output
# 
# [execution time limit] 5 seconds (r)
# 
# [input] integer n
# 
# A positive even integer.
# 
# Guaranteed constraints:
#   4 ≤ n ≤ 20.
# 
# [input] integer firstNumber
# 
# Guaranteed constraints:
#   0 ≤ firstNumber ≤ n - 1.
# n = 10
# firstNumber = 7

circleOfNumbers <- function(n, firstNumber) {
  DiagonallyOpposite = ifelse((n/2) > firstNumber,((n/2) + firstNumber),(firstNumber - (n/2)))
  return(DiagonallyOpposite)
}