【进阶实战】Lua区间合并：沙巴克活动档期的重叠归并

local function activeAt(now, spans)
    for i = 1, #spans do
        if now >= spans[i][1] and now <= spans[i][2] then
            return true, i           -- 重叠段被多次命中，叠发
        end
    end
end

-- 沙巴克攻城双倍档期归并
local function mergeSpans(spans)
    table.sort(spans, function(a, b) return a[1] < b[1] end)
    local out = {spans[1]}
    for i = 2, #spans do
        local last, cur = out[#out], spans[i]
        if cur[1] <= last[2] then
            last[2] = math.max(last[2], cur[2])   -- 重叠拉长
        else
            out[#out + 1] = cur
        end
    end
    return out
end