lua/tests/Smoke/sieve.lua
Yevhenii Shapovalov 7b824e0268 add tests
2017-11-09 13:39:24 +02:00

29 lines
736 B
Lua

-- sieve.lua
-- the sieve of Eratosthenes programmed with coroutines
-- typical usage: lua -e N=500 sieve.lua | column
-- generate all the numbers from 2 to n
function gen (n)
return coroutine.wrap(function ()
for i=2,n do coroutine.yield(i) end
end)
end
-- filter the numbers generated by `g', removing multiples of `p'
function filter (p, g)
return coroutine.wrap(function ()
for n in g do
if n%p ~= 0 then coroutine.yield(n) end
end
end)
end
N=N or 500 -- from command line
x = gen(N) -- generate primes up to N
while 1 do
local n = x() -- pick a number until done
if n == nil then break end
print(n) -- must be a prime number
x = filter(n, x) -- now remove its multiples
end