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  1. Prepare
  2. Functional Programming
  3. Memoization and DP
  4. Pentagonal Numbers
  5. Discussions

Pentagonal Numbers

  • MinhTuanTran
     + 0 comments

    The honest-but-not-DP way:

    let pentagonals = 
    seq { 1L..100000L }
    |> Seq.scan (fun pentagonal idx -> pentagonal + idx * 3L - 2L) 0L
    |> Seq.toArray

let n = Console.ReadLine() |> int
for _ in seq { 1..n } do
    pentagonals |> Array.item (Console.ReadLine() |> int) |> printfn "%d"

    The cheating way:

    let pentagonal n = n * (1.5 * n - 0.5)
let n = Console.ReadLine() |> int
for _ in seq { 1..n } do
    Console.ReadLine() |> float |> pentagonal |> int64 |> printfn "%d"