【高级技巧】Lua有序归并：裁决之杖双价目表的线性合并

local function mergePrices(a, b)
    local out = {}
    for i = 1, #a do out[#out + 1] = a[i] end
    for i = 1, #b do out[#out + 1] = b[i] end
    table.sort(out, function(x, y)
        return x.price < y.price end)      -- 白扔一次全量排序
    return out
end

-- 裁决之杖新旧价目表，各按price升序
local function mergePrices(a, b)
    local out, i, j = {}, 1, 1
    while i <= #a and j <= #b do
        if a[i].price <= b[j].price then
            out[#out + 1] = a[i]; i = i + 1
        else
            out[#out + 1] = b[j]; j = j + 1
        end
    end
    while i <= #a do out[#out + 1] = a[i]; i = i + 1 end
    while j <= #b do out[#out + 1] = b[j]; j = j + 1 end
    return out
end