Comments on: Project Euler in F# – Problem 52

By: claudio

claudio — Fri, 18 Dec 2009 13:47:59 +0000

The problem statement is ambiguous and it is not clear if repeated digits are allowed or not, but I have to agree with you that checking the frequency of each digit’s occurrence is a safer approach.

By: Darrell Plank

Darrell Plank — Fri, 18 Dec 2009 12:51:18 +0000

It would appear that your definition doesn’t work for multiple identical digits. In particular, you say you create a set partially to discard duplicates when really you don’t want to do that or you end up saying that “122″ has the same digits as “12″. It apparently works in this particular case, but strictly speaking, you should be checking the frequency of each digit’s occurence in addition to it’s mere presence. The fact that this solution works is, to some extent, luck.

By: claudio

claudio — Sat, 21 Mar 2009 16:18:32 +0000

I used Seq.map because I wanted to get a sequence of integers and not a string.

With my code, if we pass 123 as input we get [1; 2; 3;].
Without Seq.map, with the same input we get the string “123″ which is an array of characters and not integers.

However, in this case there is no difference for the final output, so using Seq.map could be avoided.

By: Freed Myers

Freed Myers — Sat, 21 Mar 2009 08:41:50 +0000

Why do the Seq.map in digits? I tried it with just n.ToString() and it seemed to work fine, though I had to change the signature to
let digits (n : int)