Roboexplore

local comp = require("component")
local robot = require("robot")
local tun = comp.tunnel
local explored = {}
local dirX = {0,1,0,-1}
local dirY = {-1,0,1,0}

local function getOff(dir, addDir)
  local resDir = (dir + addDir) % 4
  return dirX[resDir + 1], dirY[resDir+1]
end

local function isExplored(x, y)
  if explored[x] == nil then
    return false
  end
  return explored[x][y] == true
end

local function setExplored(x, y)
  if explored[x] == nil then
    explored[x] = {}
  end
  explored[x][y] = true
end

local function sendCmd(cmd, x, y)
  tun.send(cmd, x, y)
end

local function explore(x, y, dir)
  setExplored(x,y)
  sendCmd("in", x, y)
  for cd = 0, 3 do
    local xo, yo = getOff(dir, cd)
    if robot.detect() then
      sendCmd("block", x + xo, y + yo)
    else
      if not isExplored(x + xo, y + yo) then
        robot.forward()
        explore(x + xo, y + yo, (dir + cd)%4)
      end
    end
    robot.turnRight()
  end
  sendCmd("out", x , y)
  robot.back()
end

explore(0,0,0)
sendCmd("end", 0, 0)