Coinbase OA 面經大放送|演算法、SQL、邏輯題全覆蓋

要说 Coinbase OA ，真的是比一般互聯網公司的更有意思一點。 作為全球最大的加密貨幣交易平臺之一，他們在招聘環節尤其看重候選人的邏輯和代碼功底。 OA 不只是單純刷題，很多題目都帶點交易業務的味道，比如訂單撮合、價格分析或者交易異常檢測。 剛拿到題的時候，可能覺得跟常規 OA 差不多，但仔細做就會發現，細節上還是有不少坑。

Coinbase 的 OA 一般在 Codility 或 HackerRank 上測，時間大概 70 到 90 分鐘。 整體是 2 到 3 道程式設計題，有時還會摻雜一點 SQL 或者數據清洗的小題。 難度在中等偏上，主要考察三個方面：

1. 代碼的正確性（能不能跑通所有 case）;
2. 時間複雜度（別超時）;
3. 可讀性（代碼是不是清晰）。

常見題型圍繞陣列、哈希表、區間處理、字串操作，但題目背景會結合金融場景，比如撮合引擎、價格波動、異常交易檢測之類的。 做題時感覺既像演算法題，又有點業務味道。

Coinbase OA 真題分享

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 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

少走彎路，多拿 offer

Coinbase 的 OA 給我的感覺就是：不光看你能不能寫出代碼，還要看你能不能在緊張的時間里把思路理清，寫得既對又快。 如果你經常遇到“腦子裡有點思路但寫不完整”或者“卡在 debug 出不來”的情況，那真的沒必要死撐。

在 Programhelp，我們做的不只是“代寫”，而是幫你在考試中保持節奏感。 通過遠端無痕助攻，我們能及時提醒你哪些思路更高效、哪些坑要避免，甚至在關鍵 debug 節點拉你一把。 很多同學靠著這點輔助，不光順利過了 Coinbase 的 OA，還在 Robinhood、Stripe 這種金融科技公司拿到後續面試機會。

所以如果你正準備 Coinbase 的 OA，不妨找我們聊聊，少走點彎路，節省寶貴的備考時間，說不定下一個順利過關的就是你。

jor jor

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