Content
Mach Eight Sample Project
Thank you for taking the time to complete this sample project. We’re a tech first company and we value our engineers tremendously. We’re are looking for hard working, smart engineers with either excellent experience or lots of potential.
Task
The task is to write a function that finds pairs of integers from a list that sum to a given value. The function will take as input the list of numbers as well as the target sum. Sample output is shown below.
> app 1,9,5,0,20,-4,12,16,7 12
+ 12,0
+ 5,7
+ 16,-4
In the example, there is an executable named app. It takes as command line
arguments a comma separated list of integers, and the target integer. Your app
doesn’t need to have identical input/output mechanisms. For example, you could
read from a file instead of the command line.
You can assume that all input values are integers. You can assume that there aren’t
any repeat values in the list.
The algorithm to find the pairs must be faster than O(n^2). All edge cases
should be handled appropriately. This is not a closed book test. You are
encouraged to reach out with any questions that you come across.
Evaluation
All candidates who submit an algorithm that is efficient and correct will pass to the next step of the interview process. We define “efficient” as faster than O(n^2) and “correct” as returning the correct results for all possible inputs. Any assignment that doesn’t return the correct answer for the sample input above will fail. If you feel the need to impress us by going above and beyond, we’re impressed by good unit tests as well as clean and readable code. We’re less interested in your knowledge of any particular framework (react, django, etc.). You’re welcome to create a full featured web app with pretty graphics if you want, but that will not improve your chances of passing. There have been passing assignments written in under 20 lines of python.
Submission
The preferred form of submission is by publishing a public repo on github with your code and a README file explaining how to run the code.
Solution
Environment
OS: Arch Linux x86_64
Shell: GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu) and zsh 5.9 (x86_64-pc-linux-gnu)
Go: go version go1.20.4 linux/amd64
Docker: Docker version 23.0.6, build ef23cbc431(client) 9dbdbd4b6d(server)
Program
Usage
The program receives two parameters
./app <numbers separated by comma> <target sum>
Assumptions
- There are no repeated numbers
- All number are integers
- The numbers are comma separated without spaces
The program can receive repeated numbers, but, this can lead to an output with repeated pairs.
Build
We can build the program using
go build .
Or, using docker
docker run --rm -v "$PWD":/app -w /app golang:1.20 go build .
Another option to get the binary without downloading this repository directly
go install -v github.com/RichardAlmanza/other-challenges/macheight/app@latest
Using Docker
docker run --rm -v "$PWD":/go/bin golang:1.20 go install github.com/RichardAlmanza/other-challenges/macheight/app@latest
Running the program
Also, Go can Build and run a temporal binary
go run . 1,9,5,0,20,-4,12,16,7 12
Or, using docker
docker run --rm -v "$PWD":/app -w /app golang:1.20 go run . 1,9,5,0,20,-4,12,16,7 12
Using the binary compiled from the build stage
./app 1,9,5,0,20,-4,12,16,7 12
Reading from a file
Given a file, where each line has the two parameters separated by space
e.g., cases.lst
-34,-22,34,37,14,-11,-29,53,23,29,46,-33,-28 -67
-32,17,30,-16,78,-26,71,25,0,31,42,61,33,10,13,-28 31
-34,23,29,46,-32,17,30,-16,73,3,-15,-36,-8,48,76,15,-13 8
1,9,5,0,20,-4,12,16,7 12
1,9,5 6
9,3,20,28,65,29,-40,-8,55,80,70,38,64,-13,8,51,30,67,60,59 0
We can use bash to read the file and pass the parameters to the program
while read -r numbers target; do ./app $numbers $target; echo; done < cases.lst