素数判定 (試し割り法)
(NumberTheory/Prime/is_prime.py)

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• Last update: 2021-03-05 15:07:14+09:00

概要

$O(\sqrt n)$ で素数判定を行うアルゴリズム。

使い方

is_prime(x: int) -> bool
x の素数判定結果 (True: 素数である、False: 素数ではない) を返す。計算量 $O(\sqrt n)$

Verified with

• TestCase/AOJ/ALDS1_1_C.test.py

Code

def is_prime(x):
    if x == 2:
        return True
    if x == 1 or x % 2 == 0:
        return False
    for k in range(3, int(x ** 0.5) + 1, 2):
        if x % k == 0:
            return False
    return True

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.12.4/x64/lib/python3.12/site-packages/onlinejudge_verify/documentation/build.py", line 71, in _render_source_code_stat
    bundled_code = language.bundle(stat.path, basedir=basedir, options={'include_paths': [basedir]}).decode()
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.4/x64/lib/python3.12/site-packages/onlinejudge_verify/languages/python.py", line 96, in bundle
    raise NotImplementedError
NotImplementedError

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