48 lines
1.3 KiB
Python
48 lines
1.3 KiB
Python
|
#!/usr/bin/env python
|
||
|
|
# -*- coding: utf-8 -*-
|
||
|
|
|
||
|
|
"""
|
||
|
|
Obliczenie n-tego wyrazu ciągu fibonacciego na dwa sposoby.
|
||
|
|
1. Naiwna rekurencja: podstawienie do wzoru.
|
||
|
|
2. Wersja z cachem: każdy wyraz jest obliczany dokładnie raz.
|
||
|
|
"""
|
||
|
|
|
||
|
|
def naive_fibonacci(n):
|
||
|
|
if n <= 0:
|
||
|
|
return 0
|
||
|
|
if n in [1,2]:
|
||
|
|
return 1
|
||
|
|
return naive_fibonacci(n-1) + naive_fibonacci(n-2)
|
||
|
|
|
||
|
|
|
||
|
|
def cache_fibonacci(n, cache=None):
|
||
|
|
if cache is None:
|
||
|
|
cache = [None for i in range(n+1)]
|
||
|
|
cache[0] = 0
|
||
|
|
cache[1] = cache[2] = 1
|
||
|
|
return cache_fibonacci(n, cache)
|
||
|
|
else:
|
||
|
|
if cache[n] is not None:
|
||
|
|
return cache[n]
|
||
|
|
else:
|
||
|
|
cache[n] = cache_fibonacci(n-1, cache) + cache_fibonacci(n-2, cache)
|
||
|
|
return cache[n]
|
||
|
|
|
||
|
|
def non_reccurent_fibonacci(n):
|
||
|
|
cache = [None for i in range(n+1)]
|
||
|
|
cache[0] = 0
|
||
|
|
cache[1] = cache[2] = 1
|
||
|
|
for i in range(2, n + 1):
|
||
|
|
cache[i] = cache[i-1] + cache[i-2]
|
||
|
|
return cache[n]
|
||
|
|
|
||
|
|
for i in [5, 10, 15, 20, 30, 40]:
|
||
|
|
print("Naive fibonacci for ", i, ":", naive_fibonacci(i))
|
||
|
|
|
||
|
|
for i in [5, 10, 15, 20, 30, 40, 100]:
|
||
|
|
print("cache fibonacci for ", i, ":", cache_fibonacci(i))
|
||
|
|
|
||
|
|
for i in [5, 10, 15, 20, 30, 40, 100]:
|
||
|
|
print("no-recurrent fibonacci for ", i, ":", non_reccurent_fibonacci(i))
|
||
|
|
|