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"""

This is a pure Python implementation of Dynamic Programming solution to the fibonacci

sequence problem.

"""

class Fibonacci:

def __init__(self) -> None:

self.sequence = [0, 1]

def get(self, index: int) -> list:

"""

Get the Fibonacci number of `index`. If the number does not exist,

calculate all missing numbers leading up to the number of `index`.

>>> Fibonacci().get(10)

[0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

>>> Fibonacci().get(5)

[0, 1, 1, 2, 3]

"""

if (difference := index - (len(self.sequence) - 2)) >= 1:

for _ in range(difference):

self.sequence.append(self.sequence[-1] + self.sequence[-2])

return self.sequence[:index]

def main() -> None:

print(

"Fibonacci Series Using Dynamic Programming\n",

"Enter the index of the Fibonacci number you want to calculate ",

"in the prompt below. (To exit enter exit or Ctrl-C)\n",

sep="",

)

fibonacci = Fibonacci()

while True:

prompt: str = input(">> ")

if prompt in {"exit", "quit"}:

break

try:

index: int = int(prompt)

except ValueError:

print("Enter a number or 'exit'")

continue

print(fibonacci.get(index))

if __name__ == "__main__":

main()