POJ 3669 Meteor Shower

gistfile1.fs

module Util =
  let fordir x y f =
    for (dx, dy) in [ (-1, 0); (0, -1); (1, 0); (0, 1) ] do
      f (x+dx) (y+dy)

open Util

let size = System.Console.ReadLine() |> int
let inputs = [|
  for x = 0 to size - 1 do
    yield System.Console.ReadLine().Split([|' '|]) |> Array.map int
|]

let cost = Array2D.init 330 330 (fun _ _ -> System.Int32.MaxValue)

for [| x; y; t |] in inputs do
  cost.[x, y] <- min cost.[x, y] t
  fordir x y <| fun nx ny ->
    if nx >= 0 && ny >= 0 then
      cost.[nx, ny] <- min cost.[nx, ny] t

let queue = System.Collections.Generic.Queue<int*int*int>()
queue.Enqueue(0, 0, 0)

let visited = Array2D.init 330 330 (fun _ _ -> false)

exception Done
try
  while queue.Count <> 0 do
    let (c, x, y) = queue.Dequeue()
    if not visited.[x, y] then
      visited.[x, y] <- true
      if cost.[x, y] = System.Int32.MaxValue then
        printfn "%A" c
        raise Done
      fordir x y <| fun nx ny ->
        if nx >= 0 && ny >= 0 && not visited.[nx, ny] && cost.[nx, ny] > c+ 1 then
          queue.Enqueue(c+1, nx, ny)
  printfn "%A" -1
with Done -> ()