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42 lines
801 B
Python
42 lines
801 B
Python
'''
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Sieve of Eratosthenes
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Input : n =10
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Output : 2 3 5 7
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Input : n = 20
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Output: 2 3 5 7 11 13 17 19
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you can read in detail about this at
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https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes
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'''
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def prime_sieve_eratosthenes(num):
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"""
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print the prime numbers upto n
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>>> prime_sieve_eratosthenes(10)
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2 3 5 7
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>>> prime_sieve_eratosthenes(20)
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2 3 5 7 11 13 17 19
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"""
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primes = [True for i in range(num + 1)]
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p = 2
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while p * p <= num:
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if primes[p] == True:
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for i in range(p*p, num+1, p):
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primes[i] = False
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p+=1
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for prime in range(2, num+1):
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if primes[prime]:
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print(prime, end=" ")
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if __name__ == "__main__":
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num = int(input())
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prime_sieve_eratosthenes(num)
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