Day 4: Ceres Search
Megathread guidelines
- Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
- You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL
FAQ
- What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
- Where do I participate?: https://adventofcode.com/
- Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465
I tried to think of some clever LINQ to do this one, but was blanking entirely.
So naïve search it is.
C#
string wordsearch = ""; int width; int height; public void Input(IEnumerable<string> lines) { wordsearch = string.Join("", lines); height = lines.Count(); width = lines.First().Length; } public void Part1() { int words = 0; for (int y = 0; y < height; y++) for (int x = 0; x < width; x++) words += SearchFrom(x, y); Console.WriteLine($"Words: {words}"); } public void Part2() { int words = 0; for (int y = 1; y < height - 1; y++) for (int x = 1; x < width - 1; x++) words += SearchCross(x, y); Console.WriteLine($"Crosses: {words}"); } public int SearchFrom(int x, int y) { char at = wordsearch[y * width + x]; if (at != 'X') return 0; int words = 0; for (int ydir = -1; ydir <= 1; ++ydir) for (int xdir = -1; xdir <= 1; ++xdir) { if (xdir == 0 && ydir == 0) continue; if (SearchWord(x, y, xdir, ydir)) words++; } return words; } private readonly string word = "XMAS"; public bool SearchWord(int x, int y, int xdir, int ydir) { int wordit = 0; while (true) { char at = wordsearch[y * width + x]; if (at != word[wordit]) return false; if (wordit == word.Length - 1) return true; wordit++; x += xdir; y += ydir; if (x < 0 || y < 0 || x >= width || y >= height) return false; } } public int SearchCross(int x, int y) { if (x == 0 || y == 0 || x == width - 1 || y == width - 1) return 0; char at = wordsearch[y * width + x]; if (at != 'A') return 0; int found = 0; for (int ydir = -1; ydir <= 1; ++ydir) for (int xdir = -1; xdir <= 1; ++xdir) { if (xdir == 0 || ydir == 0) continue; if (wordsearch[(y + ydir) * width + (x + xdir)] != 'M') continue; if (wordsearch[(y - ydir) * width + (x - xdir)] != 'S') continue; found++; } if (found == 2) return 1; return 0; }
I haven’t quite started yet, and this one does feel like a busy work kinda problem. I was wondering if I could write something to rotate the board and do the search, but I think that might be not worth the effort