Lua字符串散列：自制哈希的均匀分布

-- 错误：只取首字母取模，分布严重偏斜
local function badHash(s, m)
    return string.byte(s, 1) % m
end

local function strHash(s, m)
    local h = 0
    for i = 1, #s do
        h = (h * 31 + string.byte(s, i)) % m
    end
    return h
end
local buckets = {}
local names = {"sword", "shield", "potion", "scroll"}
for _, n in ipairs(names) do
    local b = strHash(n, 16)
    buckets[b] = (buckets[b] or 0) + 1
end
local label = panel:getChildByName("hashText")
label:setString(tostring(buckets[strHash("sword", 16)]))