以下是一段LUA的代码，请教高手“perm{"a", "b", "c"}”为什么能返回一个table
function permgen (a, n)
if n == 0 then
coroutine.yield(a)
else
for i=1,n do
-- put i-th element as the last one
a[n], a[i] = a[i], a[n]
-- generate all permutations of the other elements
permgen(a, n - 1)
-- restore i-th element
a[n], a[i] = a[i], a[n]
end
end
end
function perm (a)
local n = table.getn(a)
local co = coroutine.create(function () permgen(a, n) end)
return function () -- iterator
local code, res = coroutine.resume(co)
return res
end
end
function printResult (a)
for i,v in ipairs(a) do
io.write(v, " ")
end
io.write("\n")
end
for p in perm{"a", "b", "c"} do
printResult(p)
end
请教高手“perm{"a", "b", "c"}”为什么能返回一个table
