`time love . > out` w/ this 4 main.lua. will see file "out"

local math_min, math_max, table_insert, table_remove = math.min, math.max, table.insert, table.remove

local maximum = {
    sharpness = 5,
    sweepingEdge = 3,
    unbreaking = 3,
    looting = 3,
    fireAspect = 2,
    knockback = 2,
    mending = 1
}

local multiplier = {
    sweepingEdge = 2,
    looting = 2,
    fireAspect = 2,
    mending = 2,
    sharpness = 1,
    unbreaking = 1,
    knockback = 1
}

local function copy(item)
    local item2 = {
        enchantments = {},
        priorWorkings = item.priorWorkings,
        type = item.type
    }
    for enchantment, level in pairs(item.enchantments) do
        item2.enchantments[enchantment] = level
    end
    return item2
end

local function combine(target, sacrifice)
    local target_priorWorkings = target.priorWorkings
    local sacrifice_priorWorkings = sacrifice.priorWorkings
    local cost =
        2 ^ target_priorWorkings - 1 +
        2 ^ sacrifice_priorWorkings - 1
    target.priorWorkings = math_max(sacrifice_priorWorkings, target_priorWorkings) + 1
    for enchantment, level in pairs(sacrifice.enchantments) do
        local l1, l2, max = target.enchantments[enchantment] or 0, level, maximum[enchantment]
        target.enchantments[enchantment] = math_min(l1 == l2 and l1 + 1 or math_max(l1, l2), max)
        cost = cost + target.enchantments[enchantment] * multiplier[enchantment]
    end

    return target, cost
end

local lowestSpentLevels = math.huge
local finalStates

local function step(state)
    for i = 1, #state do
        for j = 1, #state do
            if i ~= j then
                local stateCopy = {spentLevels = state.spentLevels, history = {}}
                for i, item in ipairs(state) do
                    stateCopy[i] = copy(item)
                end
                for i, v in ipairs(state.history) do
                    stateCopy.history[i] = v
                end
                stateCopy.history[#stateCopy.history + 1] = i
                stateCopy.history[#stateCopy.history + 1] = j

                local target, sacrifice
                if i < j then
                    sacrifice = table_remove(stateCopy, j)
                    target = table_remove(stateCopy, i)
                else
                    target = table_remove(stateCopy, i)
                    sacrifice = table_remove(stateCopy, j)
                end

                if sacrifice.type ~= "sword" then
                    target, cost = combine(target, sacrifice)
                    local stateCopy_spentLevels = stateCopy.spentLevels + cost
                    stateCopy.spentLevels = stateCopy_spentLevels
                    table_insert(stateCopy, target)
                    stateCopy.history[#stateCopy.history + 1] = cost

                    if cost < 40 then
                        if #stateCopy == 1 then
                            if stateCopy_spentLevels == lowestSpentLevels then
                                table_insert(finalStates, stateCopy)
                            elseif stateCopy_spentLevels < lowestSpentLevels then
                                lowestSpentLevels = stateCopy_spentLevels
                                finalStates = {stateCopy}
                                print(lowestSpentLevels)
                            end
                        else
                            step(stateCopy)
                        end
                    -- else "Too expensive!"
                    end
                end
            end
        end
    end
end

local function book(enchantment, level)
    return {type = "book", enchantments = {[enchantment] = level}, priorWorkings = 0}
end

step({
    history = {},
    spentLevels = 0,

    {type = "sword", enchantments = {}, priorWorkings = 0},
    book("sharpness", 4),
    book("sharpness", 4),
    book("looting", 3),
    book("unbreaking", 3),
    book("sweepingEdge", 3),
    book("fireAspect", 2),
    book("knockback", 2),
    book("mending", 1)
})


local function traverse(t, n)
    for k, v in pairs(t) do
        if type(v) == "table" then
            print(string.rep("\t", n) .. k .. ":")
            traverse(v, n + 1)
        else
            print(string.rep("\t", n) .. k .. " = " .. v)
        end
    end
end
traverse(finalStates, 0)

love.event.quit()