#! prime.py
import time
f = open("sss.txt","w")
def primes(n):
P = []
f = []
for i in range(n + 1):
if i > 2 and i % 2 == 0:
f.append(1)
else:
f.append(0)
i = 3
while i * i <= n:
if f[i] == 0:
j = i * i
while j <= n:
f[j] = 1
j += i + i
i += 2
P.append(2)
for i in range(3, n, 2):
if f[i] == 0:
P.append(i)
return P
if __name__ == '__main__':
start = time.clock()
n = 10000000
P = primes(n);
print("There are %d primes less than %d" % (len(P), n))
# for i in range(10):
# print(P[i])
print("Time: %f" % (time.clock() - start))
# for n in range(2,100000):
# if isPrime(n):
# print("%d is prime"%n)
# print("%d is "%n + ("prime" if isPrime(n) else "not prime"))
# print(primes(n),file=f)
