Lua计数排序：值域有限的线性排序

-- 错误：小值域大数组仍用比较排序，白付比较费
table.sort(values)

local function countSort(values, maxVal)
    local cnt = {}
    for _, v in ipairs(values) do
        cnt[v] = (cnt[v] or 0) + 1
    end
    local out = {}
    for v = 1, maxVal do
        for _ = 1, (cnt[v] or 0) do
            out[#out + 1] = v
        end
    end
    return out
end
local label = panel:getChildByName("sortedText")
label:setString(table.concat(countSort({3, 1, 2, 1, 3}, 3), ","))