We shall say that an
-digit number is pandigital if it makes use of all the digits 1 to
exactly once; for example, the 5-digit number, 15234, is 1 through
5 pandigital.
The product 7254 is unusual, as the identity,
, containing multiplicand, multiplier, and product is 1 through 9 pandigital.
Find the sum of all products whose multiplicand/multiplier/product identity
can be written as a 1 through 9 pandigital.
HINT: Some products can be obtained in more than one way so be sure to only
include it once in your sum.
I made a bunch of helper functions to do things like compare the digits of numbers and check if a number had a zero in it. Other than that I figured out a rough range of numbers to iterate through and checked them all. 69,644