Mandelbrot Set 358

Jesse, Hi!

Thanks for reporting this! Actually you haven't broken anything, it is timeout signalled this way (code execution is limited by 1 second I think) - but obviously I have forgotten to detect this -1 and show proper error message :(

Will fix it now (and I guess in other similar problems too).

Hm-m-m, thanks for sharing this experience! Problem of course involves calculating many points... I recently found that Lua besides standard scripting engine has also JIT implementation, which works with speed similar to programs compiled to native code (e.g. C and Go) - about 7-10 times faster. (this probably makes it language of choice in some industrial projects, i.e. Tarantool)

Probably we may add such lua-jit thing as alternative executor in the nearest future...

oh, it's me, Rodion, just from user's account while testing the feature...

As a follow-up, I managed to add LuaJIT interpreter to sandbox, and it is used by the checker for Lua problems too.

To use it, put as a first line of the program some comment containing luajit.

For example, trying to sum up square roots of numbers up to 1 million:

res = 0
for i=1,1000000 do
  res = res + math.sqrt(i)
end
print(res, os.clock())

We get 666667166.45884 0.14582 (the latter value means 146 milliseconds execution time).

Now the same with the magical comment:

--luajit
res = 0
for i=1,1000000 do
  res = res + math.sqrt(i)
end
print(res, os.clock())

Results in 666667166.45884 0.011789 (i.e. just 12 milliseconds).

Drawback is that LuaJIT doesn't support most recent language features - it is conformant to Lua 5.1 "with some syntax from 5.2 and 5.3 included".

I shall add this to our instructions.