gistfile1.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

'''
エラトステネスのふるいを用いて素数を見つける
'''

import unittest
import math


class TestPrimeSieve(unittest.TestCase):

    def setUp(self):
        self.primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29,
                       31, 37, 41, 43, 47, 53, 59, 61, 67, 71,
                       73, 79, 83, 89, 97, 101, 103, 107, 109, 113,
                       127, 131, 137, 139, 149, 151, 157, 163, 167, 173,
                       179, 181, 191, 193, 197, 199, 211, 223, 227, 229,
                       233, 239, 241, 251, 257, 263, 269, 271, 277, 281,
                       283, 293, 307, 311, 313, 317, 331, 337, 347, 349,
                       353, 359, 367, 373, 379, 383, 389, 397, 401, 409,
                       419, 421, 431, 433, 439, 443, 449, 457, 461, 463,
                       467, 479, 487, 491, 499, 503, 509, 521, 523, 541,
                       547, 557, 563, 569, 571, 577, 587, 593, 599, 601,
                       607, 613, 617, 619, 631, 641, 643, 647, 653, 659,
                       661, 673, 677, 683, 691, 701, 709, 719, 727, 733,
                       739, 743, 751, 757, 761, 769, 773, 787, 797, 809,
                       811, 821, 823, 827, 829, 839, 853, 857, 859, 863,
                       877, 881, 883, 887, 907, 911, 919, 929, 937, 941,
                       947, 953, 967, 971, 977, 983, 991, 997]

    def testPrimeSieve(self):
        self.assertEqual(self.primes, sieve(1000))


class PrimeBooler:

    def __init__(self, num):
        self.num = num
        self.flag = True


def sieve(N):
    numbers = tuple(PrimeBooler(i) for i in xrange(0, N + 1))
    prime_numbers = []
    for pb in numbers:
        num = pb.num
        if num < 2:
            continue
        if pb.flag:
            for prime_number in prime_numbers:
                if num % prime_number == 0:
                    pb.flag = False
                    break
            else:
                prime_numbers.append(num)
                for i in xrange(2, N + 1):
                    if i * num > N:
                        break
                    numbers[i * num].flag = False
    return prime_numbers


def main():
    unittest.main()


if __name__ == '__main__':
    main()