TDT4109/Exercise 3/9 - Alternerende sum/task9b.py

try:
  from common.inputChecking.typeCheck import inputTypeCheck
except ModuleNotFoundError:
  print('Sjekk README.md for hvilke flagg python trenger')
  exit(1)

def AlternateNumberGenerator():
  isEven = lambda n: n % 2 == 0
  n = 1
  counter = 2
  while True:
    yield n
    n = n + (-counter**2 if isEven(counter) else counter**2)
    counter += 1


def alternateSumStopAt(k):
  numGen = AlternateNumberGenerator()
  previousN = None
  n = next(numGen)
  iterations = 0
  while n < k:
    previousN = n
    n = next(numGen)
    iterations += 1

  print(
      f'Summen av tallene før summen blir større enn k er {previousN}. Antall iterasjoner: {iterations}'
  )


if __name__ == "__main__":
  k = inputTypeCheck('k: ', int)
  alternateSumStopAt(k)