POJ 3009 Curling 2.0

gistfile1.fs

exception Done of int
let loopEnd = ref false
while not !loopEnd do
  let [| width; height |] = System.Console.ReadLine().Split([|' '|]) |> Array.map int
  if height = 0 && width = 0 then loopEnd := true
  else
    let maze = 
      [| for x = 0 to height - 1 do
           yield System.Console.ReadLine().Split([|' '|]) |> Array.map int |]
    let start = ref (0, 0)
    let goal = ref (0, 0)
    for h = 0 to height - 1 do
      for w = 0 to width - 1 do
        if maze.[h].[w] = 2 then
          maze.[h].[w] <- 0
          start := (h, w)
        else if maze.[h].[w] = 3 then
          maze.[h].[w] <- 0
          goal := (h, w)

    let rec dfs h w c =
      if c >= 10 then 11
      else
        try
        let answer = ref 11
        for (dh, dw) in [ (-1, 0); (0, -1); (1, 0); (0, 1) ] do
          if h+dh >= 0 && w+dw >= 0 && h+dh < height && w+dw < width && maze.[h+dh].[w+dw] <> 1 then
              let i = ref 1
              let flag = ref true
              while !flag && h+dh* !i >= 0 && w+dw* !i >= 0 && h+dh* !i < height && w+dw* !i < width do
                if (h+dh* !i, w+dw* !i) = !goal then 
                  raise (Done (c+1))
                
                else if maze.[h+dh* !i].[w+dw* !i] = 0 then
                  incr i
                else if maze.[h+dh* !i].[w+dw* !i] = 1 then
                  flag := false
              if not !flag then
                maze.[h+dh* !i].[w+dw* !i] <- maze.[h+dh* !i].[w+dw* !i] - 1
                answer := min (dfs (h + dh * (!i - 1)) (w + dw * (!i - 1)) (c+1)) !answer
                maze.[h+dh* !i].[w+dw* !i] <- maze.[h+dh* !i].[w+dw* !i] + 1
        !answer
        with Done(x) -> x

    let answer = dfs (fst !start) (snd !start) 0
    printfn "%A" (if answer=11 then -1 else answer)