Some of the problems are so easy to understand and relatviely easy to work out how a program might solve it but they are a ball ache to program them. Parsing numbers into strings or reading text files into variables and analysing them etc...
TBH I tend to pass by them if I think they're going to be like that. This is one I decided to try despite that fact.
Problem 41 - find the largest n-pandigital prime number.
SOlved, runs in 0.2 seconds in C++.
0.343 seconds for me in C#, could really optimise it but don't see much point, it is on a work machine doing a lot of other things though
Ended up splitting out the concerns to a subset of numbers once I figured out the number of digits it had to have, the whole answer runs on 1 line of code calling 2 methods previously used
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Problem 41 - find the largest n-pandigital prime number.
SOlved, runs in 0.2 seconds in C++.
0.343 seconds for me in C#, could really optimise it but don't see much point, it is on a work machine doing a lot of other things though
Ended up splitting out the concerns to a subset of numbers once I figured out the number of digits it had to have, the whole answer runs on 1 line of code calling 2 methods previously used
Mine was almost brute force but not quite.
I can say that the maximum must be less than 7654321 as any number that is 8 or 9 pandigital is divisble by 9.
I used a sieve to get all the primes up to 7654321 and then went through them in reverse to find the first (or last) pandigital one.
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