Project Euler Problem 043

Statement

The number, 1406357289, is a 0 to 9 pandigital number because it is made up of each of the digits 0 to 9 in some order, but it also has a rather interesting sub-string divisibility property.

Let d1 be the 1st digit, d2 be the 2nd digit, and so on. In this way, we note the following:

* d2d3d4=406 is divisible by 2
* d3d4d5=063 is divisible by 3
* d4d5d6=635 is divisible by 5
* d5d6d7=357 is divisible by 7
* d6d7d8=572 is divisible by 11
* d7d8d9=728 is divisible by 13
* d8d9d10=289 is divisible by 17

Find the sum of all 0 to 9 pandigital numbers with this property.

Solution

Self explanatory solution.

from itertools import permutations
 
index = [0, 2, 3, 5, 7, 11, 13, 17]
 
def has_divisibility_property(n):
    str_n = str(n)
    for i in range(1,8):
        num = str_n[i:i+3]
        if int(num) % index[i] != 0:
            return False
    return True
 
if __name__ == '__main__':
    digits = set(str(x) for x in range(0, 10))
    result = 0
    for x in range(1,10):
        tmp = digits.copy()
        tmp.remove(str(x))
        result += sum(int(str(x) + ''.join(i)) for i in permutations(tmp) if
                      has_divisibility_property(str(x) + ''.join(i)))
    print("The result is:", result)

The Python fiel is available for download here.

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