b times. So I've got to go 3 b steps. All right I've got to go through the loop b times I've got three steps each time, and then when I pop out of the loop, I've got two more steps. All right I've got the initiation of answer and the return of it.
好,我一共执行了b次循环,每次循环内部进行了三次基本操作,当跳出循环后还有两个基本操作,因此这个初始的答案就是,2+3b次基本操作,来完成这个循环。
Well I ought to be able to do that by simply generalizing the loop. And that's what the next piece of code on your a hand out shows you.
好的通过生成这个循环,我应该能够达到目的,这也是你们的讲义中下一段代码。
If I want a copy of the string, I've got to whip out my week 1 skills of just iterating with a four loop from left to right and make copies of those characters.
我需要那个字符串的一个拷贝,我使用,第一周的技巧,从左到右做四次迭代,然后复制这4个字符。
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。
One of the things we said last time was, with that set of things, the ability to give values-- sorry, to give names to values-- the ability to make decisions, the ability to loop as a function of that, the ability get things in and out, we said that that actually gave us a language we said was Turing-complete.
上次我们和以上内容一起说过,我们可以赋值--抱歉,为数值命名--可以做出判断决定-,并且据此进行循环,可以输入输出数据,我们说拥有这些功能的语言,是图灵完备的。
So this do while loop immediately breaks out at the point of that check.
所以这个do,while,循环在检查的时候,直接中断了。
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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