It can be seen that the number, 125874, and its double, 251748, contain exactly the same digits, but in a different order.
Find the smallest positive integer, x, such that 2x, 3x, 4x, 5x, and 6x, contain the same digits.
// check if two numbers are permutations of the same set of digits let isPermutation number1 number2 = let str1 = number1.ToString().ToCharArray() |> Array.sort let str2 = number2.ToString().ToCharArray() |> Array.sort if str1.Length <> str2.Length then false else Array.forall2 (fun x y -> x = y) str1 str2 let answer = Seq.unfold (fun state -> Some(state, state + 1)) 1 |> Seq.filter (fun n -> [2..6] |> List.map (fun x -> x * n) |> List.forall (fun xn -> isPermutation xn n)) |> Seq.head
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I’m an AWS Serverless Hero and the author of Production-Ready Serverless. I have run production workload at scale in AWS for nearly 10 years and I have been an architect or principal engineer with a variety of industries ranging from banking, e-commerce, sports streaming to mobile gaming. I currently work as an independent consultant focused on AWS and serverless.
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