Python/dynamic_programming/fibonacci.py
Maarten 868c2fa0a8
Rewrite fibonacci.py (#5665) (#5677)
* Removed doctest call

* Removed 0 and 1 append to `fib_array`

* Moved fibonacci sequence logic into `calculate`

* Refactored `get` to generate missing numbers

* Renamed `fib_array` to `sequence`

* Renamed `number` to `index`

* Refactored `get` to only return sequence to `index`

* Moved main block into function

* Added documentation to `get`

* Added missing type hints

* Fixed doctest error in `get` docstring

* Moved calculate logic into get

* Reformatted with black

* Fixed wrong generation range
2021-10-31 22:19:44 +08:00

53 lines
1.3 KiB
Python

"""
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]
"""
difference = index - (len(self.sequence) - 2)
if difference >= 1:
for _ in range(difference):
self.sequence.append(self.sequence[-1] + self.sequence[-2])
return self.sequence[:index]
def main():
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()