5 alternatives to the Fizzbuzz test for hiring programmers
I compiled a list over the last 100 so-called programmers who came to me looking for a job. 75 of them failed one or more of our three simple programming tests. Let me emphase that; 75 out of 100 applicants to a programming job can not program. At all.
You might have heard of the Fizz Buzz test. I first read about it on Jeff Atwood’s excellent blog.
Write a program that prints the numbers from 1 to 100. But for multiples of three print “Fizz” instead of the number and for the multiples of five print “Buzz”. For numbers which are multiples of both three and five print “FizzBuzz”.
About 7 of 10 made this test, but when we took them to step two many of the programmers still could not program at all. It seems like they have read about the fizz buzz test in blogs and just repeated a solution they’d read about before the interview.
So we needed something else. We started by replacing ‘FizzBuzz’ with a different word, and saw that more people failed. Remember, the goal is not to make people fail on tests - only to quickly discard the people who can not write software at an early stage to save time and effort for both of us.
We introduced the following tests to the applicants.
Write a function that takes two words as an argument and returns true if they are anagrams (contain the exact same letters) and false otherwise.
Sometimes people don’t know what an anagram is. That is not important so we explain it to the applicant. The interesting part is to see if they solve it at all - and if they solve it in a smart way. The smartest developers almost always resort to first check the length of the words and return false directly if they are not exactly the same length. Then they sort the letters in the words alphabetically and compare the strings equality. Some people stress out over the problem and create arrays and iterate over them, keeping track of which ones are in the other words. It works, and if they are on this path they usually can write software too. The ones who shake their head and can not think of a single thing to do with the words - they seldom make it to the next interview.
Write a function that takes two arguments, an amount in dollars and a tax percentage. Return an array with the tax amount in cents.
I want the applicant to comment on why the hell we are asking him or her to return the value in an array. Otherwise, the math involved is simple enough for any programmer to know it by heart. If they start to talk about things like “I am a programmer, not a math student” don’t fall for it. This is basic math and math is an important part of programming.
3. Bug fixes
“There are three big obvious errors in the code below. Which ones?”
Used with the code below or your own internal bug-ridden code snippet in the language you are working with. Here we are using a small ruby-method:
There are actually more than three errors in this code, and its usefulness can certainly be discussed. I want the applicant to at least mention that we should be using == instead of = since the if statement will always return true. I also want them to notice that we are returning ‘name’ no matter what, and that we have a potential eternal recursion going on here.
4. Box size
“Write a function that takes three measurements in centimeters as input and returns a the volume over a litre”
Americans may need to google how much a centimeter and a litre is, but otherwise this should be an easy task for most programmers. Things I want to hear the applicant ask is _“Hmm .. what should we do if the volume is less than a litre? Return 0 or a negative number?”.
5. Worst Fizz Buzz
“Write the worst – but working – implementation of Fizz Buzz that you can think of”
This can bring up some good laughs, and takes some of the pressure off of the applicant. “Write bad code? I can do that!”. You are looking to see if they know their way around programming and ineffective code / code smells. I have seen examples with 100 if-statements, and one guy even wrote a program to output a method that repeats itself about 100 times using switch and case in PHP.
This is some of the test that I use when I hire people over at Standout and as of right now we use Devb.io to find new applicants to our jobs (skipping the high hiring fees).
I again want to emphasize that this is only to sort out the real developers from the crowd. I really don’t want to waste anyone’s time and energy on doing multiple interviews when we both can find out with a simple test that they’re not going to make it. No pointing fingers, no harsh comments - just a simple test to find who we are looking for.