45 lines
853 B
Python
45 lines
853 B
Python
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#!/usr/bin/env python3
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from random import randint
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DEPTH = 10
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def is_prime(n):
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if n == 2:
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return True
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if not n % 2 or n < 2:
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return False
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for i in range(DEPTH):
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a = randint(2, n-1)
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if pow(a, n-1, n) != 1:
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return False
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return True
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def harshad_nums(N, n=0, s=0):
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r = []
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for i in range(n==0, 10):
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m = 10*n + i
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nws = s + i
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if m > N:
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break
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if m % nws:
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continue
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r.append((m, nws))
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r += harshad_nums(N, m, nws)
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return r
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def main(N):
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for n, s in harshad_nums(N // 10):
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if not is_prime(n // s):
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continue
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for d in range(1, 10):
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m = 10*n + d
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if m >= N:
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break
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if is_prime(m):
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yield m
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N = 10**14
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print(sum(main(N)))
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