Maze Generator Using Krugrall's Randomized Algorithm

shell.run("clear")
print("Enter maze size")
write("X:");x=math.floor(tonumber(read())/2)
write("Y:");y=math.floor(tonumber(read())/2)
print("Horozontal Influence (NYI)")
print("Vertical Influence (NYI)")
read()
shell.run("clear")
visited={}
nodes={}

for i=1,y*2-1 do
  if i%2==1 then
    nodes[i]=string.rep("- ",x):sub(1,x*2-1)
  else
    nodes[i]=string.rep(" ",x*2-1)
  end
end

term.setBackgroundColor(colors.white)
for i=1,x do
  visited[i]={}
  for j=1,y do
    visited[i][j]=false
    term.setCursorPos(i*2-1,j*2-1)
    write(" ")
  end
end
visited[1][1]=true

function done()
  for i=1,x do
    for j=1,y do
      if visited[i][j]==false then return false end
    end
  end
  return true
end

function fn(sx,sy)
  u,r,d,l=false,false,false,false
  if sy>1 then if not visited[sx][sy-1] then u=true end end
  if sy<y then if not visited[sx][sy+1] then d=true end end
  if sx>1 then if not visited[sx-1][sy] then l=true end end
  if sx<x then if not visited[sx+1][sy] then r=true end end
  return {u,r,d,l}

end

function nt(tbl)
  local num=0
  for i=1,#tbl do
    if tbl[i] then num=num+1 end
  end
  return num
end

function npos(xps,yps)
  nodes[yps]=nodes[yps]:sub(1,xps-1).."-"..nodes[yps]:sub(xps+1,x*2-1)
end

while not done() do
  lst=nil
  lst={}
  for i=1,x do
    for j=1,y do
      if visited[i][j] and nt(fn(i,j))>0 then table.insert(lst,{i,j}) end
    end
  end
  rnd=#lst
  rnd=math.random(1,rnd)
  nbr=fn(lst[rnd][1],lst[rnd][2])
  nls=nil
  nls={}
  for i=1,4 do
    if nbr[i] then table.insert(nls,i) end
  end
  dir=nls[math.random(1,#nls)]
  if dir==1 then --Up
    visited[lst[rnd][1]][lst[rnd][2]-1]=true
    npos(lst[rnd][1]*2-1,lst[rnd][2]*2-2)
    term.setCursorPos(lst[rnd][1]*2-1,lst[rnd][2]*2-2)
  elseif dir==2 then --Right
    visited[lst[rnd][1]+1][lst[rnd][2]]=true
    npos(lst[rnd][1]*2,lst[rnd][2]*2-1)
    term.setCursorPos(lst[rnd][1]*2,lst[rnd][2]*2-1)
  elseif dir==3 then --Down
    visited[lst[rnd][1]][lst[rnd][2]+1]=true
    npos(lst[rnd][1]*2-1,lst[rnd][2]*2)
    term.setCursorPos(lst[rnd][1]*2-1,lst[rnd][2]*2)
  elseif dir==4 then --Left
    visited[lst[rnd][1]-1][lst[rnd][2]]=true
    npos(lst[rnd][1]*2-2,lst[rnd][2]*2-1)
    term.setCursorPos(lst[rnd][1]*2-2,lst[rnd][2]*2-1)
  end
  write(" ")
  sleep(0)
end
os.pullEvent()
handle=fs.open("LstMz","w")
for i=1,y*2-1 do
  handle.writeLine(nodes[i])
end
handle.close()
term.setBackgroundColor(colors.black)