# encoding:utf-8
# 寻找周长1000以下，能够成直角三角形最多的数
from time import time
from math import sqrt
from itertools import permutations
def getPrimes(N=50000):
l_result = [True] * N
l_result[0], l_result[1] = False, False
for i in range(0, N):
if l_result[i]:
for j in range(i * i, N, i):
l_result[j] = False
return [k for (k, v) in enumerate(l_result) if v]
def isPrime(N, l_primes):
t = int(sqrt(N)) + 1
for i in l_primes:
if i > t:
return True
if N % i == 0:
return False
return True
def euler041():
l_primes = getPrimes()
l_result = []
l_tmp = [1]
for k in range(2, 10):
l_tmp.append(k)
l_nums = permutations(l_tmp, k)
for each in l_nums:
s = ''
for i in list(each):
s += str(i)
if isPrime(int(s), l_primes):
l_result.append(int(s))
print(l_result)
if __name__ == '__main__':
start = time()
euler041()
print('cost %.6f sec' % (time() - start))
cost 1.680193 sec |
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