How many circular primes are there below one million? '''
import Functions
import time
start = time.clock()
circular_ls = [2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, 97]
primes_ls = Functions.primes_sieve(999999)
num = ''
for prime in primes_ls:
if prime > 97:
num = Functions.int_to_str(prime) # num is now a char string corresponding to the integer
num_rot = len(num) -1
while(num_rot > 0):
num = Functions.rotate(num)
if Functions.str_to_int(num) not in primes_ls:
break
num_rot -=1
if num_rot == 0:
circular_ls.append(prime) # if num_rot drops to zero, passed test, append to circular list
print('The number of circular primes < 1e6 is ',len(circular_ls))
Functions.runtime(start)
def reverse(num): num = str(num) num = num[::-1] num = Functions.str_to_int(num) return num
