/Advent-of-Code-2015

Primary LanguageRust

Advent of Code 2015

Daily Themes and Stars

  1. ** Basic programming: loops, conditions, variables, and tests.
  2. ** Splitting strings, 2D arrays, parsing integers from strings, arithmetic.
  3. ** Hashmaps (comparable objects), sets, refactoring
  4. ** Embarrassingly parallelizable problems, refactoring, use of existing libraries
  5. ** Strings, unit testing, regular expressions
  6. ** Mutable state, object-oriented programming, procedural programming, polymorphism, abstraction
  7. ** Parsing, dynamic programming, $O(2^n)$
  8. ** String encoding, look-ahead parsers (peeking)

Lessons Learned

  • I really liked go run and how Go made it so easy to build an executable from a .go file, but I never got comfortable with go install and go get from Github. rustc can compile a Rust source file directly, which is fine.
  • A cool strength Rust has over Go is that a package may contain multiple binary crates in the src\bin directory. This is the structure I'm using for Advent of Code.
  • Calls to dbg! and assert! transfer ownership of the arguments. This means you need to pass references (&) instead of values.
  • Tests in Rust are excellent! Use cargo test for all your testing needs. See day 4.
  • I would be interested to go back to day 4 to do this in parallel. This would have been easy in Go.
  • Looks like the compiler will (at least, by default) completely ignore errors (including syntax errors) in your tests.
  • Like Go, you can declare a variable in if let. For example: if let Error(e) = f(x) { g(e); }.
  • You can also while let, which avoids an implicit move of the iterator inside a for loop (see day 8).
  • Lifetime annotations might be necessary when mutating hash maps in a function.
  • The memoize library was not as effortless as @cache in Python.
  • Rayon, on the other hand, is amazing! You should be able to replace iter with par_iter for easy parallelization.

Documentation

Enter the command rustup doc to access the Rust Programming Language ("the book"), Rustonomicon, examples, API documentation, and a lot more. Examples:

rustup doc std::collections
rustup doc for