一种均匀散列方法（hash）

hash.lua

g_HashTable = 0
--创建hash表
function createHashTable()
	local tb = {};
	local _insert = function(k,v)
		if k==0 then
			k=1;
		end
		for i = k,k+999,1 do 
			if i>1000 then
				i = i-1000;
			end
			if tb[i]==nil then
				tb[i]=v;
				if i == 0 then 
					print(i,k,v)
				end
				return;
			end
		end
	end
	for i = 1,1000,1 do 
		local tmp = 131313*i+1113;
		local key = tonumber(string.sub(tmp,-4,-2)) or 1;
		_insert(key,i)
	end
	return tb;
end

--校验hash表
function judeHashTable()
	local a=0;
	local b=0;
	if g_HashTable==0 then 
		g_HashTable = createHashTable()
	end
	for i,v in pairs(g_HashTable) do
		a=a+i;
		b=b+v;
		print(i,v)
	end
	print(a,b)
end

--指定uid和命中概率q，判断用户是否命中，要求同一输入，输出唯一确定
function grayRelease(uid,q)
		local midNum = tonumber(string.sub(uid,-4,-2)) or 0;
		if g_HashTable==0 then 
			g_HashTable = createHashTable()
		end
		local hashValue = g_HashTable[midNum+1]
		if hashValue<=1000*q then
			return 1;
		end
		return 0;
end

--test，样本uid：242368487~242368487+200000-1
for i,v in pairs(arg) do
	if type(tonumber(v))=="number" then
		local count = 0;
		local n1 = 242368487;
		--local n2 = 259643522;
		for i=n1,n1+200000-1,1 do
			count = count + grayRelease(i,v)
		end
		print(v,count,count/(200000))
	end
end