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Python3.2 or higher lru_cacheで再帰をキャッシュ
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# -*- coding: utf-8 -*- | |
# | |
# フィボナッチ数列 第30項を計算する関数に | |
# lru_cacheを使って関数の呼び出し回数を比較 | |
# | |
from functools import lru_cache | |
exec_counter = 0 | |
@lru_cache(maxsize=None) | |
def fibonacci(n): | |
global exec_counter | |
exec_counter += 1 | |
if n == 0: | |
return 0 | |
if n == 1: | |
return 1 | |
return fibonacci(n - 1) + fibonacci(n - 2) | |
print(fibonacci(30)) | |
print(f"exec_count : {exec_counter}") | |
# キャッシュなし | |
# 832040 | |
# exec_count: 2692537 | |
# キャッシュあり | |
# 832040 | |
# exec_count: 31 |
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