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.