brenomfviana / vjudge-rust

Rust solutions for CodeChef and UVa problems.

VJudge Rust

Description

This repository contains Rust solutions of some CodeChef and UVa problems. These problems were homeworks for the Algorithms Project course of University of São Paulo (USP).

When I code these solutions there was no option to send Rust code to VJudge (the official code judge of our class) or another code judging system (Are we judged yet?). I also did not find any Rust solution for these problems. I solved the course homeworks by using C++, however I wanted to improve my Rust skills and develop Rust solutions could be not trivial (and were not) for some problems. Therefore, I decided to recode these homeworks by using Rust to learn the Rust way to solve problems. I have made a lot of code refactoring as you can see on the commits list. My first implementations did not have a clean code and there were a lot of improvements to make. I just did these improvements after the end of my course and I maybe do improve a little more sometime later.

Some observations

• Rust code, in some situations, can be very verbose due the use of Option, Result and HashMap;
• Rust code can be very clean, we can do a lot of things with little code;
• Reverse sort could be simpler (something like rev_sort()) not all of this: sort_by_key(|&num| Reverse(num))
• C++ HashMap is very different of Rust HashMap. The first one is really flexible, but can lead to unpredictable behaviors because an element can be created just by calling for a not added key (hmap[i]). Rust HashMap is more strict because the borrowing rules.

Some things that I missed

• Tuple assignment for already defined variables, something like:

  let (mut a, mut b) = (0, 0);
  (a, b) = (4, 2);
  

  Maybe there is a reason for Rust do not allow this, but it would make the code cleaner.
• The do...while syntax sugar. I prefer use this:

  do {
    a += 1;
  } while a > b;
  

  Instead of this:

  loop {
    a += 1;
    if a > b { break }
  }
  

  Maybe we also could have a do...while let, but I cannot think in an example of usage of this.
• A function to read char by char from an input (read_char(&mut char)):

  let mut input = char::new();
  io::stdin().read_char(&mut input);
  

  Use this function is better to use for some problems, like the last one of this repository.

List of Problems

Problem	Online Judge	Code
00-stable-marriage-problem	CodeChef	STABLEMP
01-coin-collector	UVa	11264
02-scarecrow	UVa	12405
03-match-making-problem	UVa	12210
04-backt-to-the-8-queens	UVa	11085
05-sum-it-up	UVa	574
06-rat-in-a-maze	CodeChef	MM1803
07-knuths-permutation	UVa	10063
08-9puzzle	UVa	11513
09-15puzzle	UVa	10181
10-inversions	--	--
11-solve-it	UVa	10341
12-problemk	UVa	11935
13-winterim-backpacking-trip	UVa	907
14-luggage	UVa	10664
15-supersale	UVa	10130
16-is-bigger-smarter	UVa	10131
17-let-me-count-the-ways	UVa	357
18-rare-order	UVa	200
19-counting-stars	UVa	11244
20-bicoloring	UVa	10004
21-maze-traversal	UVa	10377
22-racing	UVa	1234
23-sending-email	UVa	10986
24-wormholes	UVa	558
25-page-hopping	UVa	821
26-sabotage	UVa	10480
27-factors-and-factorials	UVa	160
28-ocean-deep-make-it-shallow	UVa	10176

License

This project is licensed under the MIT License - see the LICENSE file for details.