Programming Polyglots: Pair to learn

11 Mar 2020

Two people pair up to accomplish problems using a language that neither of them knows well. Provided problems are based on programming interview questions.

This exercise was originally presented at the Recurse Center to combine its two great loves: learning and community! The point is to expose yourself to the fringes of your language knowledge. And who knows, maybe you’ll be inspired to use it for an upcoming project.

Language Rundown

Established

C, C++, C#, Java, Python, JavaScript / ECMAScript, Ruby

Rising

Go, Rust, Haskell, Scala, OCaml, Lua, Erlang / Elixir, Clojure, Factor, F#, Elm

Fun / Esoteric

LOLCODE, Piet, Befunge, Brainf*ck, Shakespeare

Retro

Perl, COBOL, Spitbol / Snobol, BASIC / Visual Basic, Excel, Assembly (any flavor)

Pairing Exercises

Tackle these exercises in whatever order you’d like. Some of them may be unsuitable or downright impossible in the language of choice, so feel free to choose anything from the list. HackerRank’s 30 Days of Code might also be good inspiration.

Getting started

• Hello world: or make sure you can run anything
• FizzBuzz: prints the numbers from 1 to 100, but for multiples of 3 print “Fizz” instead of the number, for multiples of 5 print “Buzz”, for numbers which are multiples of both three and five print “FizzBuzz”.”

Numbers

• Max Contiguous Sum: given an array of ints, find the largest number you can create by summing adjacent / contiguous elements, e.g. [ 1 -3 2 3 -10 ] would give 5 because of the 2 and 3
• Two Sum: given a list of numbers and a target, print the pairs that sum up to the target, using each number only once, e.g. [ 1 3 4 0 -1 2 1] and target 3 gives (1,2), (3,0), (4,-1). The second occurence of 1 is unused.
• Reverse an integer: e.g. “1234” becomes “4321”

Strings

• String to Integer (atoi): function that takes a string of digits and converts it to an integer, e.g. "2455" becomes 2455
• Trim whitespace: with or without libraries, function that takes a string with leading / trailing whitespace, and eliminate it, e.g. “ some stuff “ becomes “some stuff”
• Remove redundant spaces: function that takes a string that may contain consecutive spaces among normal characters, and remove extra spaces, e.g. “this is a test” becomes “this is a test”
• Anagrams in a string / file: given an input word and a longer string, find all anagrams of that word in the longer string, e.g. “listen” and “please be silent” returns “silent”

Data Structures

• List: define the type / class / struct or use language features, and build it
• Cycles (may not work for all languages): define a function to test if a list has cycles, e.g. 1 -> 2 -> 3 -> 4 is good, but 1 -> 2 -> 3 -> 4 -> 2 .... is not
• Binary tree: define the type / class / struct, create ways of building it up
• Flip a binary tree: reverse the left and right children of a tree, e.g. 2 2 3 4 becomes 4 3
• Output left child below a certain level: printLeftChild(Tree root, int level) to only output the left child of a binary tree past a certain level

Meta

• Print 1-1000 without using loops or “if” statements. Some languages do not support this… or do they?