POJ 1979 Red and Black

gistfile1.fs

let blackTile = '.'
let redTile = '#'
let man = '@'
let loopEnd = ref false
while not !loopEnd do
  let [|I; J|] = System.Console.ReadLine().Split([|' '|]) |> Array.map int
  if I = 0 && J = 0 then
    loopEnd := true
  else
    let maze = 
      [| for x = 0 to J - 1 do
           yield System.Console.ReadLine().ToCharArray() |] 

    let startI = ref 0
    let startJ = ref 0
    for i = 0 to I - 1 do
      for j = 0 to J - 1 do 
        if maze.[j].[i] = man then
          startI := i
          startJ := j

    let count = ref 1
    let rec dfs i j =
      if maze.[j].[i] = blackTile then
        maze.[j].[i] <- '#'
        incr count
      for (dj, di) in [ (-1, 0); (0, -1); (1, 0); (0, 1) ] do
        if j+dj >= 0 && i+di >= 0 && j+dj < J && i + di < I && maze.[j+dj].[i+di] = blackTile then
          dfs (i+di) (j+dj)
      
    dfs !startI !startJ
    printfn "%A" !count