Formula
CommonFun.GetRandom
function CommonFun.GetRandom(array, index)
local MAX_RANDOM_INDEX = 100
local group = math.ceil(index / 5)
local key = index - math.floor(index / 5) * 5
key = key ~= 0 and key or 5
if array[group] == nil or index > MAX_RANDOM_INDEX then
return 0, index
end
local groupValue = array[group]
local value = math.floor(groupValue / math.pow(100, 5 - key)) % 100
local newIndex = index == MAX_RANDOM_INDEX and 1 or index + 1
return value, newIndex
end