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Up on the screen, I've got-- I commented it out, but I've got a piece of code that you've seen before, right up here. OK?
我现在在大屏幕上标出来的,是你们以前看过的一段代码,就在这儿？
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All right so-- yeah, how do I get to the code for that? That's interesting.
噢，我是怎么写出这个的代码,这件事儿挺有意思的。
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- Writing code that just looks-- I'm not even sure what this is supposed to look like, a little flower or pinwheel or something like that.
这代码写出来有点像-,我不确定这像什么，像朵花，或纸风车，或其他什么东西。
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Again, I want you to start seeing how to map the characteristics of the code- the characteristics of the algorithm, let's not call it the code-- to the complexity.
是算法中的那些特性,我们还是别说代码了，转化为复杂度-,我一会儿还会再讲点儿这个的，但是我们再看一个例子。
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Right, and just to get a sense of this, let's look at a simple little example, so on your hand-out, you'll see I've got a little piece of code that says assuming I've got one of these points, I want to do things with it, for example I might want to add them together.
这些数组中的一个，你怎么能够知道，它是哪种类型的呢？,你怎么知道它是以笛卡尔坐标,表示的还是以极坐标,形式表示的呢？,你没有可以用来区分的东西，你没有说明这种信息,聚集实际上的意义。
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So let's look at the second example, all right, I keep doing that -- this piece of code from here to here gives me a way of now creating a hash table of size 256.
所以让我们来看一下第二个例子，好的，我继续做那件事,这段代码中从这里到这里,是创建一个大小为256的哈希表。
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And in particular, if I think about that problem - actually I want to do this- if I think about that problem, I'm going to write a little piece of pseudo code.
关于这个问题尤其要注意的是,实际上当我考虑这个-,问题的时候我想这么做，我会去写一点伪代码。
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OK? And in fact, if you look at the code up here, and it's on your handout, the very first one, x 1, right here- if I could ask you to look at it-- is a piece of code to do it. And I'm less interested in the code than how we're going to analyze it, but let's look at it for a second.
实际上，如果你看看,你们课堂发的材料上面的代码，第一页上的，就是那-,大家请看看实现的这一部分代码,我不太关心,我们会怎么解释这个代码,首先让我们先看看。
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to do sqrt, or square root-- no, I'm going to square root use sqrt, that's the name I'm using here-- square root a hundred different places in some piece of code. Without function, I'd have to copy that piece of code everywhere.
让我做一下准备,想象一下我要调用sqrt或者-,不，我会调用sqrt函数,这是我在这里用的名字，我得把这段代码到处复制。
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I can't rely on Professor Guttag if I give this- if this code to him, I can't rely on him to type in a float. Actually I can, because he's a smart guy, but in general, I can't rely on the user-- I wouldn't do it right to see if you did.
当Guttag使用这段代码的时候-,我不能相信他一定会输入一个浮点数,实际上我能因为他很聪明，但是总体上来讲，别相信用户一定会按照规则来-,我会故意做错来试试你的程序的。
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All right. If you flip to the second side of your handout, you'll see that I have a piece of code there, that does this-- let me, ah, I didn't want to do that, let me back up slightly- this is the algorithm called search.
你可以看到实现这个功能的代码,让我，额，我不想这么做,让我们回来一点,这就是命名为search的算法-,我们来看看这个算法吧。
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