problem-041.py

### 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?

### Solution

from itertools import permutations

# Function to determine if prime
def isPrime(n: int) -> bool:
    if n < 2:
        return False
    elif n == 2:
        return True
    else:
        i = 2
        while i ** 2 <= n:
            if n % i == 0:
                return False
            i += 1
        return True


digits = [1, 2, 3, 4, 5, 6, 7, 8, 9]
largest_num = 0

for a in range(1, len(digits)):
    currDigits = digits[0:a]
    numbers = list(permutations(currDigits))
    nums = []

    for i in numbers:
        currNum = 0
        for j in range(len(i)):
            currNum += (10 ** (len(i) - (j + 1))) * i[j]
        nums.append(currNum)

    for i in nums:
        if isPrime(i):
            if i > largest_num:
                largest_num = i

print("The largest pandigital prime is: " + str(largest_num))