ProjectEuler41

2017/10/26

  • 問題

Problem 41:Pandigital prime
We shall say that an n-digit number is pandigital if it makes use of all the digits 1 to n exactly once. For example, 2143 is a 4-digit pandigital and is also prime.

What is the largest n-digit pandigital prime that exists?

  • 解答例
import itertools

def isPrime(num):
    if num <= 1:
        return False
    elif num == 2 or num == 3:
        return True
    if num % 2 == 0 or num % 3 == 0:
        return False
    if not(num % 6 == 1) and not(num % 6 == 5):
        return False
    i = 5
    while i * i <= num:
        if num % i == 0 or num % (i + 2) == 0:
            return False
        i += 6
    return True

p = list(map("".join, itertools.permutations(1234567)))

max = 0
for n in p:
    if isPrime(int(n)) and max < int(n):
        max = int(n)

print(max)