open System
open System.Threading

let searchMaxInRange (arr:int[]) l r :int =
  let mutable res = 0
  if r>=arr.Length then for x=l to arr.Length-1 do
    if arr.[x]>res then res <- arr.[x]
  else do
     for x=l to r do
     if arr.[x]>res then res <- arr.[x]
  res

let searchMax (arr:int[], threadNumber:int) =
  let length = arr.Length
  let res = ref 0
  let step = length / threadNumber + 1
  let threadArray = Array.init threadNumber (fun i ->
      new Thread(ThreadStart(fun _ ->
          Monitor.Enter(arr)
          let threadRes = searchMaxInRange arr (i * step) ((i+1) * step - 1)
          if (threadRes>res.Value) then res := threadRes
          Monitor.Exit(arr)
        ))
    )
  for t in threadArray do
    t.Start()
  for t in threadArray do
    t.Join()
  printfn "%A" res.Value
0

[<EntryPoint>]
let main argv =
    0 // return an integer exit code


//[<TestCase ([|112;113;11;55;22;111;10;1|], 5, Result = 113)>]
//[<TestCase ([|111110;0;1;0;25;0;1111111111;|], 2, Result = 1111111111)>]
//[<TestCase ([|0;0;0;25;0|], 2, Result = 25)>]
//[<TestCase ([||], 2, Result = 0)>]
//let ``Test`` (arr : int[], t : int) =
  //searchMax (arr, t)