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  • Their fall from the tower sends Ethic and Hedge

    譯者: Lilian Chiu 審譯者: H_L Au

  • spinning into the rapids of a river of pure energy.

    《用程式設計師的方式思考》

  • This torrent flows from the Bradbarrier all the way to Huxenborg.

    地點:哈林堡 地點:198 森林

  • There an entire city's worth of factories

    第八集:挑戰

  • build the robots and house the Node of Memory,

    艾希克和海吉從塔上落下之後,

  • the last of the three powerful artifacts Ethic needs to collect.

    便天旋地轉地落入 純能量的急流當中。

  • After a long day and a longer night

    這條洪流從八達圍 一路流到哈森堡。

  • they find themselves in a canyon of brick and steel.

    在那裡,有相當於 一整個城市的工廠,

  • Just when they're about to reach the end of the line,

    用來建造機器人和存放記憶之泉,

  • a rope catches them.

    正是艾希克必須要收集的 三項強大寶物的最後一項。

  • Their savior, Lemma, has been waiting for them.

    在經過漫長的一天 和更漫長的一夜之後,

  • When Ethic claimed the Node of Creation from the forest tower,

    他們到了一個由磚塊 和鋼鐵形成的峽谷。

  • radios all across the land came back to life.

    他們快要到達盡頭時,

  • Adila, the resistance leader, immediately started contacting her allies,

    一條繩索套住了他們。

  • none more important than Lemma,

    他們的救星雷瑪 一直在那裡等他們。

  • a brilliant scientist working from within Huxenborg to bring down the machines.

    當艾希克從森林中的高塔 取得創造之泉時,

  • Unfortunately, the radios also tipped off the robots.

    各地的無線電都恢復通訊了。

  • So they've taken defensive measures

    反抗軍領袖艾迪拉馬上 就開始聯絡她的盟友,

  • to protect the final artifact in its home in the very heart of the city.

    當中最重要的就是雷瑪了,

  • There's only one way to get there: the gauntlet of forking paths.

    她是個聰明的科學家, 在哈森堡內部努力破壞機器。

  • It's a deadly series of luminous conveyors that wind underneath Huxenborg.

    不幸的是,無線電 也將消息走漏給機器人。

  • Starting from the current position,

    於是,它們採取了防禦措施,

  • each section runs for a distance, then splits in two.

    保護身處在城市核心的 最後一項寶物。

  • Every branch does the same thing, again and again.

    要到達只有一種方法,岔路挑戰。

  • There are thousands of branches.

    這個挑戰是在哈森堡地下 一連串的致命迂迴發光輸送帶。

  • Only one path leads to the artifact; all the others to destruction.

    從目前的位置開始,

  • Fortunately, the Node of Creation has granted Hedge a strange power:

    每段輸送帶會輸送一段距離, 接著便一分為二。

  • he can produce slightly smaller versions of himself.

    每個分支都會不斷重覆這個流程。

  • Each version can do only two things: radio information back to its parent,

    總共有數千條分支。

  • and produce slightly smaller versions of itself

    只有一條路通往寶物,

  • which can do the same two things, as can their children,

    其他則全部都通往死亡。

  • for as many generations as needed.

    幸運的是,創造之泉 將一種奇特的力量賦予海吉:

  • A patrol is closing in on their position, so Ethic's time is limited.

    它能製造出它自己的 複製品,但比較小。

  • What instructions should she give Hedge to find the one safe path?

    每一個複製品都會做兩件事:

  • Pause the video to figure it out yourself.

    把資訊用無線電回傳給它的母體,

  • Hint in 3

    以及再複製出比較小的自己,

  • Hint in 2

    而這些複製品同樣也會 做這兩件事,以此類推,

  • Hint in 1

    有必要就可以一直產生新世代。

  • Programmers have an elegant tool in their arsenal called recursion.

    巡邏兵正在靠近,所以時間有限。

  • Recursion is when you have a set of instructions that refers back to itself.

    她應該給海吉什麼指令, 才能找到那唯一一條安全的通路?

  • It's like using a word in its own definition,

    如果想要自己解題,請在此暫停。

  • except where that's frowned upon, this is incredibly effective.

    提示即將公佈:五

  • Recursion involves repetition, but in a different way than loops.

    提示即將公佈:三

  • Where a loop takes one action and repeats it again and again,

    提示即將公佈:一

  • recursion will start an action, and before it's finished, use it again,

    程式設計師有項利器,叫做遞迴。

  • and before that's finished, use it again, and so on.

    當你有一組指令,又會導至 它自己本身時,就叫做遞迴。

  • It keeps doing this until some end state is reached.

    就像是在一個詞的定義中 用到這個詞一樣,

  • It then passes the information back up, layer after layer,

    差別在於不能使用它時, 這就是非常有效的方法。

  • until it reaches the top and ends the cycle.

    遞迴會涉及重覆,但和迴圈不同。

  • Recursion is ideal for problems that involve self-similarity,

    迴圈是不斷重覆同一個動作,

  • where each part resembles the larger whole.

    遞迴會從一個動作開始, 在它結束之前,又再次使用它,

  • Like, for example, a deadly defense system designed to end any person or thing

    在那結束之前, 又再使用它,以此類推。

  • who dares tread upon it.

    遞迴會這樣不斷進行下去, 直到達成某種終止狀態。

  • Pause the video to figure it out yourself.

    接著,就會把資訊一層一層回傳,

  • Solution in 3

    直到資訊傳到頂層, 循環就此結束。

  • Solution in 2

    遞迴很適合用來解決 和「自相似」有關的問題,

  • Solution in 1

    也就是每個部分 都和更大的整體很相似。

  • Ethic's conundrum seems sprawling on the surface,

    就像是這個致命的防禦系統,

  • but there's a remarkably simple solution to it using recursion.

    設計的目的是要消滅 任何有膽踏上它的人或物。

  • In order to find it, let's first look at the simplest version of this puzzle:

    如果想要自己解題,請在此暫停。

  • what if the entire maze were just two paths?

    解答即將公佈

  • If Hedge copies himself, the copy that goes the wrong way will be destroyed.

    艾希克的難題在表面上 看似雜亂無規則,

  • So the other one, which will reach the artifact,

    但其實若會用遞迴, 就有一個非常簡單的解法。

  • can radio back the path it took, and then no matter which way is correct,

    為了要解題,我們先來看看 這個謎題最簡單的版本:

  • that's the answer Hedge will receive.

    如果整個迷宮只有兩條路呢?

  • This is called the "base case" of the recursion.

    如果海吉複製它自己, 走錯路的複製品會被摧毀。

  • Now, suppose the maze branches twice from the starting point,

    所以,另一個複製 就會抵達寶物所在,

  • and at every intersection, Hedge's copies

    用無線電回傳它走過的路徑資訊,

  • let's call them Twig 1 and Twig 2—

    不論哪條路是對的路, 那就是海吉會收到的答案。

  • make more copieslet's call them Leaves 1 through 4.

    這就叫做遞迴的「基本情況」。

  • Three Leaves will be destroyed.

    假設迷宮從起始點開始 就有兩倍的岔路,

  • The one that reaches the artifact will radio back the right answer,

    在每個路口,海吉的複製品——

  • but only to its parent.

    咱們就稱它們為 小枝一號和小枝二號——

  • So if Twig 1 or 2 is waiting at an intersection

    會產生更多複製品—— 稱為小葉一號到小葉四號。

  • and hears something over the radio,

    會有三個小葉複製品被摧毀。

  • that's the right way to go to the artifact from where it is.

    抵達寶物所在的那個小葉 會將正確答案用無線電回傳,

  • To tell Hedge the right answer from his perspective,

    但只會傳給它的母體。

  • the Twig should say which way it went,

    如果小枝一號 或小枝二號在路口等候,

  • and then the route it just heard over the radio.

    從無線電聽到消息,

  • This same process will work no matter how many times the maze branches.

    那就是從它的所在 通往寶物的正確路線。

  • Any answer a copy hears on the radio

    小枝要從它的角度 把正確答案告訴海吉,

  • must be the way to the control room from its location,

    就應該要說出它去過哪裡,

  • and if it then adds the branch it took,

    以及它從無線電所聽到的路線。

  • it can tell its parent how to get there as well.

    不論迷宮的分岔有多少, 同樣的流程都行得通。

  • We can sum up the instructions in an action called Pathfinder

    任何複製品從無線電聽到的答案

  • that every version of Hedge will follow:

    都是從它的所在 到達控制室的路徑,

  • 1. If you've reached the artifact,

    如果再加上它自己走的岔路,

  • radio to your parent whether you got there by going left or right.

    它就可以告訴它的母體 如何到達那裡。

  • 2. When you reach an intersection, move off the conveyor

    我們可以把指令總整成 一個動作,叫做「找路程式」,

  • and send new copies down the left and right paths.

    每個版本的海吉複製品 都要遵循這個程式:

  • Have them each run Pathfinder.

    一、如果你到了寶物的所在,

  • This is where recursion comes in,

    用無線電告訴你的母體你怎麼走到 那裡(用左轉、右轉來表述)。

  • and this may happen many times before the last instruction triggers, which is:

    二、當你到達路口時, 離開輸送帶,

  • 3. If you hear anything over the radio, you should radio to your parent

    派遣新的複製品 去走左、右兩條路。

  • whether you got to your spot by going left or right,

    要求它們都要執行「找路程式」。

  • then repeat everything you just heard.

    這就是要用到遞迴的地方了,

  • Pathfinder is an example of what programmers call functions,

    這個指令可能要執行許多次, 才會啟動最後一個指令,即:

  • subroutines, or procedures.

    三、如果你從無線電收到資訊, 你就要用無線電聯絡你的母體,

  • No matter the terminology, the idea is the same

    說明你是怎麼到你的所在 (用左轉、右轉來表述),

  • it's a set of instructions given a label so that it can be easily reused

    接著再重述你從無線電 聽到的所有資訊。

  • perhaps even by itself.

    「找路程式」就是程式設計師

  • And in our case that'll work perfectly

    所謂的函數、子程式,或程序。

  • an entire network of paths mapped using just three instructions.

    不論用哪個術語稱呼, 背後的想法都相同——

  • So here's what happens.

    把一組指令包裝起來, 貼上標籤,方便重覆使用——

  • By the time the patrol rounds the corner, Ethic and Lemma have improvised disguises.

    甚至可以被它自己使用。

  • They try to confuse the bots long enough to buy Hedge time.

    在我們的例子中, 採用它就非常完美——

  • Finally, Hedge's radio crackles to life with a series of directions.

    只用三條指令 就能繪製出整個網絡。

  • The three dive onto the conveyor and flee for their lives,

    接著發生的狀況是:

  • with a squadron of enforcer bots in hot pursuit.

    當巡邏兵到轉角時,

Their fall from the tower sends Ethic and Hedge

譯者: Lilian Chiu 審譯者: H_L Au

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B1 中級 中文 TED-Ed 無線電 寶物 程式 母體 重覆

The Gauntlet | Think Like A Coder, EP 8 (The Gauntlet | Think Like A Coder, Ep 8)

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    林宜悉 發佈於 2021 年 01 月 14 日
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