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p037.py
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p037.py
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import datetime
from prime import is_prime
def from_right(num):
string = str(num)
length = len(string)
for beg in range(length):
if not is_prime(int(string[beg:])):
return False
return True
def main():
L = [[2, 3, 5, 7]]
size = 1
while True:
l = []
for i in L[size - 1]:
num = i * 10
for j in [1, 3, 7, 9]:
if is_prime(num + j):
l.append(num + j)
if len(l) == 0:
break
L.append(l)
size += 1
res = 0
for (i, l) in enumerate(L):
if i == 0:
continue
for x in l:
if x % 10 in (3, 7) and from_right(x):
res += x
return res
beg = datetime.datetime.now()
ans = main()
end = datetime.datetime.now()
print("answer:", ans)
print("time:", end - beg)