Aims
The aim of this exercise is to test your ability to write a working program in Go.
• We are looking for you to demonstrate that you can write good solid code, and debug it to get a good working solution. We consider it preferable to have a good solution that is finished and works rather than half-written code that tries to be too clever.
• Comments in your code will help us understand what you are trying to do in your program. But you can assume we are not stupid.
• We are looking for a pragmatic solution with the right trade-offs between performance and reliability given the time constraints.
• We are interested in allowing you to demonstrate your ability to design and implement data structures and algorithms to solve problems, so use of any language standard container libraries is not permitted (Go maps are NOT ALLOWED, Go slices are allowed). The use of I/O streams is permitted, the use of Go "string" type is NOT ALLOWED.
• You will be asked to explain the design of your solution and talk us through the code.
• Most candidates take between 1 and 5 hours. Please do not spend longer than 6 hours on this task. In any case, please indicate approximately how long you spent writing your solution.
Languages and Tools
• The reference platform for the task is a Linux 64bit system. If you do not have access to such a platform you should implement it on a Linux or Windows environment of your choosing, however, you should be prepared to explain how your solution may need to be modified to run on the reference platform.
• The solution is to be written entirely in Go.
• Your program should also handle binary files (e.g. /boot/vmlinuz) without crashing.
The Problem
Given the attached text file as an argument, your program will read the file, and output the 20 most frequently used words in the file in order, along with their frequency. The output should be the same to that of the following bash program:
#!/usr/bin/env bash
cat $1 | tr -cs 'a-zA-Z' '[\n*]' | grep -v "^$" | tr '[:upper:]' '[:lower:]'| sort | uniq -c | sort -nr | head -20