Lua组合数：连乘递推的精确求值

local function combFact(n, k)
    local num, den = 1, 1
    for i = 1, k do
        num = num * (n - i + 1)
        den = den * i
    end
    return num / den
end

local function comb(n, k)
    if k > n - k then k = n - k end
    local r = 1
    for i = 1, k do
        r = r * (n - k + i) / i
    end
    return r
end
local p = getplayerbyname("comb01")
sendmsg(p, 1, "C(20,3)=" .. comb(20, 3)
    .. "，C(52,5)=" .. comb(52, 5))