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The idea behind all these algorithms is that what's ultimately important is how many comparisons you ultimately need to make.
这些算法的思想是,你最终需要做多少次的比较,这才是真正重要的。
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Alright, so we can implement any number of algorithms using this thing because the basic mechanism I have here is a comparator.
好了，利用它我们可以实现,很多种算法,因为在此我用到的基本原理是一个比较器。
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Or another way of saying it is, we're going to use as the basic steps, those operations that run in constant time, so arithmetic operations.
我们用可以在恒定时间内完成的操作,算法，比较,内存读取。
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I'm going to set up an index, which is going to tell me where to look, starting at the first part of the list, right?
索引告诉我从哪里开始检索数组，对不对？,然后我会去记录下我做了多少次比较，这样我就能看到这个算法的工作量了？
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Selection sort too really reduces to a total number of comparisons because I'm again comparing the current smallest to the next thing I see, the next thing, so really a lot of these sorting algorithms boil down to comparisons and the numbers that you actually have to make.
选择排序也可归纳为总数的比较,因为要将当前最小者与下一个进行比较,接着再下一个，可见,很多排序算法都可归结为比较,以及需要比较的次数。
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Typical characterization, not all the time, but typical characterization, is an algorithm that reduces the size of a problem by one, or by some constant amount each time, is typically an example of a linear algorithm.
我们学习过了线性算法，它的典型特征，不是通用的,但是比较典型的特征是，它是逐一减小问题的大小的，或者说是每次减小常数的大小。
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Where a step is a comparison or an arithmetic operation.
第一步肯定是比较,或者进行某种算法的操作。
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So we're to assume we can get to any piece of data, any instruction in constant time, and the second assumption we're going to make is that the basic primitive steps take constant time, same amount of time to compute. Again, not completely true, but it's a good model, so arithmetic operations, comparisons, things of that sort, we're all going to assume are basically in that in that particular model.
因此如果我们假设在恒定的时间内,我们可以取得任何一块数据,任何一种数据结构的话,我们要做的第二个假设就是,基本的原始操作计算花费的时间是恒定的,这个假设也不是完全正确的，但这个模型其实挺不错的，因此算法操作，比较，这一类的事情，我们在这个特定的模型中都假设是基本的,操作，花费的时间是恒定相同的。
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