“My smallest code interpreter (aka Brainfk)**” is a coding puzzle that people can be attempted in the following languages: javascript, python, ruby, haskell, clojure, java, crystal, php, cpp, typescript, rust, c, bf, coffeescript, swift, csharp, elixir, dart, groovy, and kotlin.
- Difficulty: 5 kyu
- Stars: 1115
- Votes: 966
- Category: algorithms
- Tags: Algorithms, Interpreters, Logic, Esoteric Languages
- Source: codewars
Description
Inspired from real-world Brainf**k, we want to create an interpreter of that language which will support the following instructions:
-
>increment the data pointer (to point to the next cell to the right). -
<decrement the data pointer (to point to the next cell to the left). -
+increment (increase by one, truncate overflow: 255 + 1 = 0) the byte at the data pointer. -
-decrement (decrease by one, treat as unsigned byte: 0 - 1 = 255 ) the byte at the data pointer. -
.output the byte at the data pointer. -
,accept one byte of input, storing its value in the byte at the data pointer. -
[if the byte at the data pointer is zero, then instead of moving the instruction pointer forward to the next command, jump it forward to the command after the matching]command. -
]if the byte at the data pointer is nonzero, then instead of moving the instruction pointer forward to the next command, jump it back to the command after the matching[command.
The function will take in input…
- the program code, a string with the sequence of machine instructions,
- the program input, a string, eventually empty, that will be interpreted as an array of bytes using each character’s ASCII code and will be consumed by the
,instruction
… and will return …
- the output of the interpreted code (always as a string), produced by the
.instruction.
Implementation-specific details for this Kata:
- Your memory tape should be large enough - the original implementation had 30,000 cells but a few thousand should suffice for this Kata
- Each cell should hold an unsigned byte with wrapping behavior (i.e. 255 + 1 = 0, 0 - 1 = 255), initialized to 0
- The memory pointer should initially point to a cell in the tape with a sufficient number (e.g. a few thousand or more) of cells to its right. For convenience, you may want to have it point to the leftmost cell initially
- You may assume that the
,command will never be invoked when the input stream is exhausted - Error-handling, e.g. unmatched square brackets and/or memory pointer going past the leftmost cell is not required in this Kata. If you see test cases that require you to perform error-handling then please open an Issue in the Discourse for this Kata (don’t forget to state which programming language you are attempting this Kata in).
For BF: The code and input are separated by `'!'`.
Solve It Here
Click the link below to solve it on Codewars:
Notes
This puzzle was posted by a Slackbot via a slash command. If you want to help work on the app, send a message to @Josh.
If you don’t want to see the coding puzzles when you visit the forum, you can go into your settings and mute the puzzles category.