Can you solve the locker riddle? - Lisa Winer

11,508,100 views ・ 2016-03-28

TED-Ed


请双击下面的英文字幕来播放视频。

翻译人员: Mingyu Cui 校对人员: Zhenning YANG
00:06
Your rich, eccentric uncle just passed away,
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你有钱又古怪的叔叔去世了,
00:10
and you and your 99 nasty relatives have been invited to the reading of his will.
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你和你的99个恶心的亲戚 被邀请到他遗嘱的宣读会。
00:16
He wanted to leave all of his money to you,
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他想要把所有钱留给你,
00:19
but he knew that if he did, your relatives would pester you forever.
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但他知道如果他这么做了, 你的亲戚会永远缠着你。
00:24
So he is banking on the fact
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所以他只能寄希望于
00:27
that he taught you everything you need to know about riddles.
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他教给过你的所有猜谜技巧
00:32
Your uncle left the following note in his will:
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你叔叔在遗嘱中写道:
00:35
"I have created a puzzle.
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“我设计了一个谜题。
00:37
If all 100 of you answer it together, you will share the money evenly.
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如果你们100个人一起回答, 就100个人均分我的钱。
00:42
However, if you are the first to find the pattern and solve the problem
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但是,如果你是第一个 找到答案解决问题的人
00:46
without going through all of the leg work,
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而没有用暴力跑腿法,
00:48
you will get the entire inheritance all to yourself.
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你将会独享我的所有遗产。
00:52
Good luck."
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祝你好运。”
00:54
The lawyer takes you and your 99 relatives to a secret room in the mansion
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律师把你和99个亲戚 带到了宅第的密室。
00:58
that contains 100 lockers,
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这有100个储藏柜,
01:01
each hiding a single word.
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每个柜子里藏着一个词。
01:04
He explains:
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他说:“
01:05
Every relative is assigned a number from 1 to 100.
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每个亲戚被分发1到100里的一个数字。
01:09
Heir 1 will open every locker.
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1号继承人要打开每个储藏柜。
01:12
Heir 2 will then close every second locker.
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2号将关上偶数号码的储藏柜。
01:16
Heir 3 will change the status of every third locker,
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3号改变整除3的储藏柜的状态,
01:20
specifically if it's open, she'll close it,
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如果储藏柜开着,那就关上,
01:23
but if it's closed, she'll open it.
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如果储藏柜关着,那就打开。
01:26
This pattern will continue until all 100 of you have gone.
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100个人都按这个规律执行。
01:31
The words in the lockers that remain open at the end
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最终开着的柜子里的词,
01:34
will help you crack the code for the safe.
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会帮你打开保险箱。
01:38
Before cousin Thaddeus can even start down the line,
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在1号继承人开始打开柜子之前,
01:42
you step forward and tell the lawyer you know which lockers will remain open.
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你就大步向前告诉了律师哪些柜子会是开着的。
01:49
But how?
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怎么做到的呢?
01:51
Pause the video now if you want to figure it out for yourself!
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如果你想自己想,就暂停视频!
01:54
Answer in: 3
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3秒后出答案
01:55
Answer in: 2
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2秒后出答案
01:56
Answer in: 1
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1秒后出答案
01:58
The key is realizing that the number of times a locker is touched
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关键是算出每个柜子被改变状态的次数
02:02
is the same as the number of factors in the locker number.
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是和柜子号码的因子数相同的。
02:06
For example, in locker #6,
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比如对于6号柜子,
02:09
Person 1 will open it,
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1号继承人把它打开,
02:10
Person 2 will close it,
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2号把它关上,
02:12
Person 3 will open it,
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3号把它打开,
02:14
and Person 6 will close it.
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最后6号把它关上。
02:17
The numbers 1, 2, 3, and 6 are the factors of 6.
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1,2,3,6就是6的四个因数。
02:22
So when a locker has an even number of factors
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所以如果一个柜子有偶数个因数,
02:25
it will remain closed,
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它最后就是关着的,
02:26
and when it has an odd number of factors,
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如果一个柜子有奇数个因数,
02:28
it will remain open.
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它就是开着的。
02:30
Most of the lockers have an even number of factors,
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大多数柜子有偶数个因子因数,
02:33
which makes sense because factors naturally pair up.
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因为因数自然是成对出现的。
02:37
In fact, the only lockers that have an odd number of factors
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实际上,仅有的几个有奇数个因数的柜子
02:41
are perfect squares
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是完全平方柜^_^
02:43
because those have one factor that when multiplied by itself equals the number.
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因为它们有一个因数自己乘自己得到柜号
02:48
For Locker 9, 1 will open it,
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对于9号柜子,1号继承人把它打开,
02:51
3 will close,
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3号把它关上,
02:52
and 9 will open it.
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最后9号把它打开。
02:54
3 x 3 = 9,
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3 x 3 = 9,
02:57
but the 3 can only be counted once.
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但是3只能算一个因数。
02:59
Therefore, every locker that is a perfect square will remain open.
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因此,每个完全平方柜最后是开着的。
03:04
You know that these ten lockers are the solution,
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你知道了这十个柜子就是答案,
03:07
so you open them immediately and read the words inside:
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所以你立刻打开了它们。里面写着:
03:11
"The code is the first five lockers touched only twice."
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“保险箱的密码是前五个只被碰了两次的柜子。”
03:17
You realize that the only lockers touched twice have to be prime numbers
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你发现满足条件的是质数柜
03:21
since each only has two factors:
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因为它们每个只有两个因数:
03:24
1 and itself.
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1和它本身。
03:26
So the code is 2-3-5-7-11.
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所以密码是2-3-5-7-11。
03:30
The lawyer brings you to the safe,
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律师把你带到保险箱前,
03:33
and you claim your inheritance.
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你获得了你叔叔的遗产。
03:35
Too bad your relatives were always too busy being nasty to each other
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你的亲戚光顾着互相恶心了
03:38
to pay attention to your eccentric uncle's riddles.
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没注意你的怪叔叔出的题
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