电子白板 矢量 编码

by Andy Tiffany

通过安迪·蒂芙尼(Andy Tiffany)

当涉及白板编码采访时，请记住准备 (When it comes to whiteboard coding interviews, remember to PREP)

PREP is a mnemonic I created to help you remember the steps involved in solving whiteboard coding problems. It stands for Parameters, Return, Example, Pseudocode.

PREP是我创建的助记符，旨在帮助您记住解决白板编码问题所涉及的步骤。 它代表着对于P arameters，R E打开，E xample，P seudocode。

The mnemonic is new, but the underlying technique is battle tested. This is essentially a beginner-friendly version of test-driven development that lends itself well to coding challenges.

助记符是新的，但是基础技术已经过战斗测试。 这本质上是测试驱动开发的初学者友好版本，非常适合编码挑战。

Let’s get right to it and learn PREP through an example problem. We’ll use JavaScript, but this technique works for just about any programming language.

让我们开始吧，并通过示例问题学习PREP。 我们将使用JavaScript，但是该技术几乎适用于任何编程语言。

面试官要求您编写一个函数，该函数接受一个句子并返回最长的单词。 你是做什么？ (Your interviewer asks you to write a function that accepts a sentence and returns the longest word. What do you do?)

“ P”代表参数 (“P” is for Parameters)

Most problems involve writing a function. In this step you need to determine what parameters your function should accept. Then you need to give them meaningful names.

大多数问题涉及编写函数。 在此步骤中，您需要确定函数应接受哪些参数。 然后，您需要给他们起有意义的名字。

Keywords like “takes in” or “accepts” in the problem statement will guide you here. If it’s unclear, you can also ask the interviewer for clarification. In your case, the statement “accepts a sentence” tells you that the function should accept a single string parameter.

问题陈述中的诸如“接受”或“接受”之类的关键字将为您提供指导。 如果不清楚，您也可以要求面试官澄清。 在您的情况下，语句“接受句子”告诉您该函数应接受单个字符串参数。

So you’ve determined the type of your parameter. But what should you name it? It might sound simple, but good naming is a crucial programming skill, and it takes practice.

因此，您已经确定了参数的类型 。 但是你应该给它起什么名字呢？ 听起来可能很简单，但是良好的命名是一项至关重要的编程技能，需要实践。

You could call yours “sentenceString,” but calling it “sentence” is more concise and still makes it clear we’re dealing with a string.

您可以将其称为“ sentenceString”，但将其称为“ sentence”更为简洁，但仍然清楚地表明我们正在处理字符串。

Since this is your first step, you also need to think of a meaningful name for your function itself. In your case, “longestWord” is both concise and descriptive. Now that you’ve decided this, you can write the shell for your function like this:

因为这是第一步，所以您还需要为函数本身考虑一个有意义的名称。 就您而言，“ longestWord” 既简洁又具有描述性。 现在，您已经决定了这一点，您可以像下面这样为您的函数编写外壳程序：

“ R”代表退货 (“R” is for Return)

What does this function return? Is it a number? A boolean? A string?

此函数返回什么？ 是数字吗 一个布尔值？ 弦吗？

Remember: the value a function returns is not the same as what it might display in a print/log statement.

请记住：函数返回的值与它在print / log语句中可能显示的值不同。

Once again, you can look at the problem statement for clarification. “Returns the longest word” tells you that you’re returning a word, and you know that words are strings. Let’s make this crystal clear by creating a variable to represent this return value and rigging up your function to return it. Even though you aren’t returning the correct answer yet, you’re set up to return the correct type. You have created a placeholder that will make the next steps easier.

再一次，您可以查看问题说明以进行澄清。 “返回最长的单词”表示您正在返回一个单词，并且您知道单词是字符串。 让我们通过创建一个代表该返回值的变量并装配函数以返回它的方法来使这一水晶变得清晰。 即使您尚未返回正确的答案，也可以将其设置为返回正确的类型。 您已经创建了一个占位符，它将使下一步变得更容易。

以“ E”为例 (“E” is for Example)

Even for expert developers, static code is harder to understand than running code. You want to make your code runnable and “alive” as soon as possible. You can breathe life into your function with an example test invocation.

即使对于专家开发人员，静态代码也比运行代码更难理解。 您希望尽快使代码可运行并“运行”。 通过示例测试调用，您可以为函数注入生命。

You know that if your function accepts the sentence, “I saw a hippopotamus,” it should return the string “hippopotamus” once it’s properly working. But for now, you just want to see your placeholder value from the last step to confirm your code is runnable and setup correctly.

您知道，如果您的函数接受“我看见了河马”这一句子，则在其正常工作后应返回字符串“ hippopotamus”。 但是现在，您只希望从最后一步中看到占位符值，以确认代码可运行并正确设置。

最后一个“ P”代表伪代码 (The last “P” is for Pseudocode)

While it’s tempting to just dive in and start coding now, it would be too easy to get caught up in a detail that could distract you from the bigger picture. You need to devise a strategy first, and pseudocoding is just the tactic for this.

尽管现在就开始潜入并开始编写代码很诱人，但是陷入一个细节可能太容易了，而细节可能使您无所适从。 您需要首先设计一个策略，而伪编码只是为此的策略。

Pseudocode is a series of precise statements written in spoken language comments that describe what you need to do.

伪代码是一系列用口语注释编写的精确语句，它们描述了您需要执行的操作。

您已完成PREP。 现在您可以编码了！ (You’ve finished PREP. Now you can code!)

The four steps in PREP helped you clearly frame the problem and think about how to solve it. In truth, accurate framing is half the battle. Most interviewers will already be impressed to see your methodical approach. At this point, your goal is to just write code that will make your examples and tests pass. You’ll do this by encoding each of your pseudocode steps.

PREP中的四个步骤可帮助您清楚地解决问题并思考如何解决。 实际上，准确的构架是成功的一半。 大多数面试官都会对您的系统方法印象深刻。 此时，您的目标是只编写使您的示例和测试通过的代码。 您将通过对每个伪代码步骤进行编码来做到这一点。

You know you’ve got a working solution when you can run your code and see the correct output.

您知道可以运行代码并查看正确的输出时，已经有了可行的解决方案。

You’ve made it through the hardest part now. You can breathe a sigh of relief that you’ve at least gotten to a working solution. At this point, there are just two more questions to think about:

您已经完成了最困难的部分。 您至少可以找到可行的解决方案，然后松一口气。 此时，只需要考虑两个问题：

• Are there any edge cases that would break the code? For example, do you need to take into account sentences that have a period at the end of them? You’ll write more test cases for these edge cases, then fix the code if necessary.
  是否有会破坏代码的边缘情况？ 例如，您是否需要考虑结尾处带有句点的句子？ 您将为这些极端情况编写更多的测试用例，然后在必要时修复代码。
• Can you make the code cleaner or more efficient now? You should discuss ideas with the interviewer so that they know your thoughts before risking breaking the solution.
  您现在可以使代码更整洁或更有效吗？ 您应该与面试官讨论想法，以使他们在冒险破解解决方案之前了解您的想法。

That’s it! This process might seem overly mechanical at first, but trust me, it will become second nature — much like the steps in learning to drive. Even after programming for more than 12 years, this is still roughly the sequence I follow when I’m problem solving. I’d more likely use a formal testing framework instead of log statements like we did here, but the steps are the same either way.

而已！ 这个过程乍一看似乎过于机械化，但是请相信我，它将成为第二自然-就像学习驾驶的步骤一样。 即使经过12年以上的编程，这仍然大致是我解决问题时遵循的顺序。 我更可能使用正式的测试框架来代替日志语句，就像我们在这里所做的那样，但是两种方法的步骤都是相同的。

Now you try it! Here are a few beginner-level problems you can practice with, in roughly ascending order of difficulty:

现在您尝试一下！ 您可以按照一些难度从小到大的顺序练习一些初学者级的问题：

1. Suppose you have an array of string like [ “adios”, “bye”, “ciao” ]. Your task is to write a function called total_characters that accepts such an array as a parameter and returns the summed number of characters across all the strings in the array.
   假设您有一个字符串数组，例如[“ adios”，“ bye”，“ ciao”]。 您的任务是编写一个称为total_characters的函数，该函数接受这样的数组作为参数，并返回数组中所有字符串的字符总数。
2. Write a function to flip a coin n times that returns the numbers of times a “heads” was flipped.
   编写一个将硬币翻转n次的函数，该函数返回“正面”翻转的次数。

3. (From Free Code Camp) We’ll pass you an array of two numbers. Return the sum of those two numbers, and all numbers between them. The lowest number will not always come first. Try using PREP to set this up yourself first, but then feel free to confirm your setup and finish solving it here.

   (来自Free Code Camp )我们将为您传递两个数字组成的数组。 返回这两个数字之和，以及它们之间的所有数字。 最低的数字不一定总是排在最前面。 尝试先使用PREP自己进行设置，然后随时确认您的设置并在此处完成解决。

PREP has already helped several First Step Coding learners ace their coding interviews, and I hope it can help you too. Happy coding!

PREP已经帮助一些“ 第一步编码”学习者获得了他们的编码面试机会，我希望它也能为您提供帮助。 编码愉快！

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翻译自: https://www.freecodecamp.org/news/before-you-code-remember-to-prep-for-your-coding-interview-2ccfb58147db/

电子白板 矢量 编码