Coinbase OA Interviews｜Algorithm, SQL, Logic questions are covered.

要说 Coinbase OA ，真的是比一般互联网公司的更有意思一点。作为全球最大的加密货币交易平台之一，他们在招聘环节尤其看重候选人的逻辑和代码功底。OA 不只是单纯刷题，很多题目都带点交易业务的味道，比如订单撮合、价格分析或者交易异常检测。刚拿到题的时候，可能觉得跟常规 OA 差不多，但仔细做就会发现，细节上还是有不少坑。

Coinbase's OA is usually tested on Codility or HackerRank and takes about 70 to 90 minutes. It's 2 to 3 programming questions overall, sometimes with a little SQL or data cleaning thrown in. The difficulty level is medium to high, and there are three main areas that are examined:

1. Correctness of the code (can it run through all cases);
2. Time complexity (don't time out);
3. Readability (is the code clear).

Common questions revolve around arrays, hash tables, interval processing, string manipulation, but the background of the topic will be combined with financial scenarios, such as aggregation engine, price volatility, abnormal transaction detection and so on. Doing the questions feels like both algorithmic questions, but also a bit of business flavor.

Coinbase OA Real Questions Sharing

Question 1

What does event.stopPropagation() Do?

Select the correct answer.

• It stops the event from bubbling through the element’s descendants.
• It stops the default behavior of the element being clicked.
• It stops other event handlers on the element from firing.
• It stops the event from bubbling through the element’s ancestors.
• I don’t know

Question 2

In what order does f receive its arguments?

Language: Javascript

f("foo");  
setTimeout(function() { f("bar"); }, 0);  
f("baz");  

Select the correct answer.

• foo baz bar
• foo bar baz
• foo baz
• bar foo baz
• I don’t know

Question 3

What does the following code do?

Language: Javascript

str.split("dog").join("cat")  

Select the correct answer.

• Replaces every occurrence of the word “dog” in a string with the word “cat”
• Finds the word “dog” in a string, and appends “cat” at that location
• Creates an iterator from “dog” to “cat” in the string
• Appends “dogcat” to the end of a string
• I don’t know

Question 4

Which of the following selectors will make Text pink?

Language: Html

Select the correct answer:

Replaces every occurrence of the word "dog" in a string with the word "cat"
Finds the word "dog" in a string, and appends "cat" at that location
Creates an iterator from "dog" to "cat" in the string
Appends "dogcat" to the end of a string
I don't know
Question 20
Which of the following selectors will make Text pink?

Language: Html

Select the correct answer.

• div.elem { color: pink; }
• #id { color: pink; }
• .wrapper.elem { color: pink; }
• .wrapper:nth-child(1) { color: pink; }
• I don’t know

Question 5

What technique would dramatically improve the performance of the following function?

Language: Plain

fun fib(n: Long): Long {  
    return if (n <= 1) n else fib(n - 1) + fib(n - 2)  
}  

Select the correct answer.

• recursion
• bytecode compilation
• Memoization
• divide-and-conquer algorithm
• I don’t know

Question 6

Consider the following Javascript code. The final output to the console is 0. Why?

Language: Javascript

function incr(num) {  
    this.count++;  
}  

incr.count = 0;  

let i;  
for (i=0; i<10; i++) {  
    if (i > 5) {  
        incr(i);  
    }  
}  

console.log(incr.count);  

Select the correct answer.

• this In incr doesn’t have a reference to incr.count.
• There’s a bug in the for-loop.
• This is caused by Javascript’s hoisting mechanism.
• console.log is async and therefore doesn’t reflect the most up-to-date value.
• I don’t know

Question 7

Which of the following is not an accurate statement regarding CAPTCHAs?

Select the correct answer.

• They have been criticized for exploiting unwitting labor
• They are used to distinguish users and bots
• Input solutions are manually verified
• A common implementation is based on the recognition of distorted text
• I don’t know

Get more offers with fewer detours

Coinbase's OA gives me the impression that it's not only about whether you can write code, but also about whether you can clear your mind in a tight timeframe and write correctly and quickly. If you often encounter the situation that "you have some ideas in your head but can't complete them" or "you are stuck in a debug", there is really no need to hold on to your life.

Exist ProgramhelpWe don't just "write for you", we help you stay on track during the exam. Through remote assistance, we can remind you which ideas are more efficient, which pitfalls to avoid, and even give you a hand at critical debugging points. Many students rely on this assistance, not only successfully passed the Coinbase OA, but also in Robinhood, Stripe and other financial technology companies to get follow-up interviews.

So if you are preparing for Coinbase's OA, you might want to talk to us and take the road less traveled, save valuable preparation time, and maybe you'll be the next one to pass the exam with flying colors.

Jory Wang Amazon Senior Software Development Engineer

Amazon senior engineer, focusing on the research and development of infrastructure core systems, with rich practical experience in system scalability, reliability and cost optimization. Currently focusing on FAANG SDE interview coaching, helping 30+ candidates successfully obtain L5/L6 Offers within one year.

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