Are You a Winner of the Alpaca Algo Trading Coding Challenge?

See Who Is Heading to the Front of the Line for Exclusive First Look Access.

Three weeks ago we threw down a challenge — solve our coding challenge and you’d go to the front of the line for those waiting to get the first look at our commission free algo trading platform.

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Here’s the challenge we issued on May 3.

Medium - Puzzle Snippet.png

Many tried, but few succeeded in solving this puzzle. In fact, fewer than half (39 percent) of those who submitted answers were able to get the correct answer. Others found their way to the front of the line by sharing the coding challenge with friends.

Today we’re releasing the emails of those who solved the challenge and are sitting on their royal thrones right at the front of our waitlist.

See all the winners here.

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If you gave it a shot, but didn’t quite get the answer right, here’s the way the puzzle was solved:

Overall it looks like a python code snippet but also includes some pseudo-math type of expressions. Let’s start by taking apart this puzzle line by line.

Line 1 

This line talks about a URL to the JSON file. If you open this URL with your browser, it should start like this.

{“date”: [“2015–07–10”, “2015–07–11”, “2015–07–12”, “2015–07–13”, “2015–07–14”, “2015–07–15”, “2015–07–16”, “2015–07–17”, “2015–07–18”, “2015–07–19”, “2015–07–20”, “2015–07–21”, “2015–07–22”, “2015–07–23”, “2015–07–24”, “2015–07–25”, “2015–07–26”, “2015–07–27”, “2015–07–28”, “2015–07–29”, “2015–07–30”, “2015–07–31”, “2015–08–01”, “2015–08–02”, “2015–08–03”, “2015–08–04”, “2015–08–05”, “2015–08–06”, “2015–08–07”, “2015–08–08”, “2015–08–09”, “2015–08–10”, “2015–08–11”, “2015–08–12”, “2015–08…

Yes, it is a JSON with keys of “date”, “open”, “high”, “low”, “close” and “volume”. Looks like some kind of historical price data. Makes sense. Alpaca is about algo trading.

Line 2 

This line was apparently a bit tricky. The quiz meant to be as simple as literal python code to slice the string variable “file” and get “-100” as an integer but some people thought it was meant to slice the content of JSON file.

Line 3 

MA here is the Moving Average function, which is a basic indicator derived from some historical price data, and typically it takes the input data and the time period of average as the parameters.

Line 4 

Calculates MA but with unknown X, and X is the set of number that satisfies this condition.

Line 5 

What is the minimum value in X?

In short, the puzzle is asking:

Using this historical price data (line 1), let m be the 5-day moving average of open prices on 100 days (line 2) before 04/01/2018 (line 3). Find the minimal (line 5) day moving average of close prices on the same day whose absolute difference from m is bigger than the fraction of square root 2 (line 4)?

If you use python and pandas, you can find the answer in a few tens of line of code with brute-force loop and get the answer of 61. This is the correct answer.

Now that you have the answer and took a look at the JSON file content, here is another short, fun quiz. Can you tell what kind of data it is? We’ll let you know the answer in the next week update, so please do not forget to be on the email list if you haven’t already!

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It’s not too late to get your own spot in line to get an exclusive first look at Alpaca. Just go to https://alpaca.markets to enter your email and we’ll make sure you get in before the stampede!

 

 

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