Question

以下代码查找| c[0] | c[1] | c[2] | c[3] | c[4] | c[5] | x a \0 \0 \0 c c c \0 \0 b b \0 \0 \0 j \0 \0 \0 \0 a \0 \0 \0 \0 d \0 \0 \0 \0给出值列表。 maxLen是一个可变值。如何删除它以进行更多功能练习？

maxLen

Answer 1

如果您更改getNewPostAndSetMaxLength以获取当前最大长度并返回一对(pos, maxLength)，则可以使用List.fold：

let getNewPosAndSetMaxLength maxLen pos len = // For each new position, check if the result of `getLenth pos` is larger than previous ones.
    let direction = if len < 1 then -1 else 1
    let newPos = 
        match [1..abs(len)] |> List.tryFind (fun i -> reject (pos + i * direction)) with
        | Some p -> p
        | None -> pos + len
    let newLen = getLength newPos
    let maxLen' = if newLen > maxLen then newLen else maxLen
    (newPos, maxLen')

[<EntryPoint>]
let main argv = 
    let (lastPos, maxLen) = [3; -2; 6; 7] |> List.fold (fun (pos, maxLen) x -> 
        getNewPosAndSetMaxLength maxLen pos x) (0, 0)
    printfn "%d" maxLen
    0 // return an integer exit code

如何删除代码中的全局可变变量？

1 个答案: