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Next time through the loop it goes to a squared.
循环完后变成a的平方。
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All right, you can see that this little piece of code, it's got a loop in there, and what's it doing?
好，你们看到的这一小块代码,是做了一个循环吧？,他在做什么？
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Well, we say at the top of the loop, when it goes up and comes down the velocity is 0.
在曲线顶端,当物体上升,然后速度为0时候
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If we weren't so pressed for time, I kinda wanna see how long we could get away with this before it gets awkward, but that, in fact, is an infinite loop t hat's hopefully deliberate.
如果有时间，我想看看,我们需要花多长时间解决这一问题，事实上，它是我故意,使用的无穷循环。
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It could run and give you the right answer, it could crash, it could loop forever, it could run and apparently give you the right answer.
它可能会正确运行,并返回给你一个正确的答案，它可能会崩溃，它可能会一直运行下去，它可能会运行并给你正确的答案。
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Once each time. Right? I only do one swap potentially, it-- though not one potentially, each time at the end of the loop I do a swap.
每次循环做一次，对么？我其实,就可能做了一次交换，也许并不是可能，每次循环的结束我都得做一次交换。
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So this is a nice little search-- sorry, a nice little sort algorithm . And in fact, it's relying on something that we're going to come back to, called the loop invariant.
恩，这是一个很棒的小搜索，抱歉，和很棒的小排序算法，事实上，它依赖于一些我们要回顾的东西,被称作循环不变量。
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By two, by two, by two, and here it just conceptually is why this thing doesn't infinitely loop.
除以2，除以2，除以2，这里只是概念性地说明这一,过程为何不会无限循环。
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And we won't wait here one hundred seconds for it to finish, but we're using the loop, we're updating a variable, and we're formatting it in a nice way.
我们将不会再这里等待100秒来等它完成,但是我们使用循环，我们更新一个变量，我们把它排成一个漂亮的格式。
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So in a sense, that's a good infinite loop that is as long as you're using the program, it's constantly checking your grammar and spelling, and underlining things, so infinite loops aren't necessarily bad if the objective is actually being met.
因此从这个意义上说，这是个好的无穷循环,只要你开始使用这个软件，它不停的检查你的语法，拼写或者下划线等，通过这种方式达到目标的时候,这样的无穷循环并不总是坏的。
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If you look at solve 2, it's going to solve2 run through the same kind of loop, printing out all of the answers.
我会让你们看一看,如果你在看，那将运行相同的循环。
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The loop invariant what does the loop invariant mean? It says, here is a property that is true of this structure every time through the loop.
循环不变量是什么意思？,它是一个在结构体中,每次循环都为真的属性。
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Oh, there's a man at the store and now we have a loop where he is just looking through my inventory one at a time and reciting what it is I actually picked up.
商店里有一个人,现在我们有一个循环,通过这个循环他可以看到我的库存,然后显示出来我实际上都采摘了哪些水果。
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Well, you'll know when it crashes, that doesn't help you very much, but you can't always tell whether something's stuck in an infinite loop or whether it's simply taking a long time to compute.
好，你将学到它在什么时候会崩溃，这对你帮助并不大，但是你不能辨别出到底是在一个循环中,有什么东西卡住了呢,还是程序需要很长的时间来计算一个结果呢。
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swap I'm going to keep track of a little variable called swap, it's initially true, and as long as it's true, I'm going to keep going, but inside of the loop I'm going to set it to false, and only if I do a swap will I set it to true.
我打算跟踪一个小的变量称为,初始值为真，只要它是真的,算法就会继续，但是在循环里,我打算把他设为假,除非交换发生，就把它设为真。
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They're running through a loop. It's a common way of thinking about problems.
有继承意义的迭代程序了,它们是以循环的模式来运行的。
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It's basically cycling through the loop a multiplying by a each time.
这个代码就是简单的循环,每次乘一个。
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And I need to initialize it outside of the loop.
我需要初始化它。
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> David: We'll let it loop once more.
>，大卫：我们再放一次音乐。
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But that little short hand there is doing exactly the same thing. It is adding that value into some digits and putting it back or signing it back into some digits. And I'll walk through that loop and when I'm done I can print out the total thing does. And if I do that, I get out what I would expect.
加上得到的这个数的,但是这个缩写声明其实是进行了同样的操作,它把我们得到的这个数加到一个数上面去,然后用和对这个数进行了重新赋值,在循环中会去遍历字符串，当完成循环后,程序会显示数字的总和，如果我运行，这个程序的话，我会得到我期待的结果。
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Otherwise, it's a pretty bad mistake, but sometimes you do want an infinite loop, Word for instance, Microsoft Word if you use it or pages or the like on your Mac or PC.
否则，它将会是一个错误，但有时你确实需要一个无穷循环，例如微软的,当你在Mac或者PC上使用它时。
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So first time through the loop, the answer is a. Second time it-sorry, as it enters the loop, at the time it enter exits a the answer is a.
当第一次完成循环的时候，答案是a，第二次，对不起，在第一次进入循环的时候,答案就是。
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I'm going to give a name to that. And what you see there is I'm going to call divisors initially an empty tuple, something has nothing in it. Right here. And then I'm going to run through the same loop as before, going through this set of things, doing the check.
你们可以看到这里,我初始化一个空的元组,名为divisiors，这里，然后我会去运行,跟以前一样的循环，遍历这个集合内的东西,然后做检查，现在我要做的是，每次我找到了一个除数我要把它收集起来。
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And then I run a loop in which I read something in, I check to see if it's the right type, if it is, I change that variable to say it's now the correct type, which means the next time through the loop, I'm going to say I'm all set and I'm going to bounce out.
因为我还没输入，然后我运行一个循环,循环内部我输入一些东西,然后看看是不是正确的类型,如果是的话我改变input，Ok为真，来证明输入数是正确的类型，这就意味着下一次运行这个循环的时候,就可以跳出循环继续执行了。
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Well, this question mark becomes an O, this question mark becomes an O, and then the loop terminates 0 1 2 because it's iterating from zero to N so that's zero, 1, 2 and the length of the string is 3 so the loop terminates, but I remember that I needed to have this special sentinel value so I'm just going to put it there manually.
嗯，这个问号变成了，这个问号变成了0，然后循环结束了,以为迭代从0到N，那就是，字符串的长度是3，然后循环就结束了，但是我记得我需要这个特殊的标记值,所以需要手动的加上它。
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I can write it explicitly. I can write it inside of a FOR loop. And we've started to add, and we'll see a lot more of this, examples of collections of structures so that we don't just have to do something that can be easily described as walking through a set of things but can actually be a collection that you walk through.
我可以明确的写出来,我可以把它在FOR循环的内部写出来，然后我们开始学习了add这个运算符,我们会在以后学习很多的,集合的数据结构的例子,这样一来我们可以进行一些,很简单的遍历集合的操作,我想要为大家指出的最后一件事情是。
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So the question was, why is this return down at this level, it says, well if I ever execute out of this FOR loop, I get to the end of the FOR loop without hitting that branch that took me through the return, then and only then do I want to actually say, gee, I got to this place, there isn't any value to return, none I'm going to return none and none.
问题是，为什么它是在这个级别上返回值呢，意思就是如果我出了这个for循环,就意味着我运行的过程中没有走到任何,带return的支路上去,这时也只有这时我才能说天呐,我终于走到这儿了，这时不会返回任何值，只会返回none和。
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If it isn't, then I'm going to go back around the loop, and notice what happens. If I get all the way around the loop, that is, all the way through that FOR loop and I never find a path that takes me through here, then the last thing I'm going to do is return a pair or a tuple with a special simple number none twice.
如果没有,我会回到循环看看发生了什么,如果我运行了整个循环,也就是整个for循环,我仍没有找到符合条件的路径,那么我最后做的事情就是返回一对,或者一个数组的两次none值。
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