Lua柱状图最大矩形：高度的边界扩展

local function largestSlow(h)
    local best = 0
    for i = 1, #h do
        local minH = h[i]
        for j = i, #h do
            minH = math.min(minH, h[j])
            best = math.max(best, minH * (j - i + 1))
        end
    end
    return best
end

local function largestRect(h)
    local stack, best = {}, 0
    local i = 1
    while i <= #h + 1 do
        local cur = (i <= #h) and h[i] or 0
        while #stack > 0
            and h[stack[#stack]] >= cur do
            local top = table.remove(stack)
            local left = stack[#stack] or 0
            best = math.max(best,
                h[top] * (i - left - 1))
        end
        stack[#stack + 1] = i
        i = i + 1
    end
    return best
end
local p = getplayerbyname("rectH01")
sendmsg(p, 1, "最大矩形 "
    .. largestRect({2, 1, 5, 6, 2, 3}))