Merge pull request #24 from Arxcis/day03/c

Solve day03 in c

Author: Arxcis

CONTRIBUTING.md

@@ -8,10 +8,11 @@
 4. Test your solution.
 
 ```sh
-../languages/python.sh day-03/input.txt day-03/output.txt day-03/solutions/super-optimized.py
+cd days/day03
+../../languages/python.sh input.txt output.txt solutions/super-optimized.py
 ```
 
-5. Add the test to `day03/test.sh`, to let the CI know how to test your solution. 
+5. Add the test to `day03/test.sh`, to let the CI know how to test your solution.
 6. Make a Pull Request to the `main` branch.
 7. One of the maintainers will merge when the tests pass!
 8. Remember to have fun :tada:

README.md

@@ -1,18 +1,19 @@
 # adventofcode2020 🕯️ 🎄 ⛄
 
-Welcome to this community project, where we collaboratively solve the 2020 edition of https://adventofcode.com/. 
+Welcome to this community project, where we collaboratively solve the 2020 edition of https://adventofcode.com/.
 
 ### [CONTRIBUTING.md](./CONTRIBUTING.md)
 
-Anyone is encouraged to contribute, and as a contributor you may do whatever you want with this code. Treat it as your own :+1: 
+Anyone is encouraged to contribute, and as a contributor you may do whatever you want with this code. Treat it as your own :+1:
 
 A shout-out to the developers over at Maritime Optima - https://github.com/orgs/MaritimeOptima/people - volunteering to support this project :pray:
 
 Also a big thanks to the rest of our contributors :tada:
 - @Celebrian
-- @Avokadoen 
+- @Avokadoen
+- @Stekpotet
 
-Contributors are welcomed to join our private leaderboard :sunglasses: Use the join code **376961-8a514359** at https://adventofcode.com/2020/leaderboard/private 
+Contributors are welcomed to join our private leaderboard :sunglasses: Use the join code **376961-8a514359** at https://adventofcode.com/2020/leaderboard/private
 
 If you enjoy working on this project, consider sharing it with your friends. The more the merrier 🚀
 
@@ -52,12 +53,12 @@ If you enjoy working on this project, consider sharing it with your friends. The
 
 | Language | Command                                        | # of days completed |
 |----------|------------------------------------------------|---------------------|
-| c        | gcc     main.c -o out.gcc && ./out.gcc         |        1 / 25       |
-| c++      | g++     main.cpp -o out.g++ && ./out.g++       |        1 / 25       |
-| python   | python3 main.py                                |        1 / 25       |
+| python   | python3 main.py                                |        3 / 25       |
+| sml      | polyc   main.sml -o out.polyc && ./out.polyc   |        3 / 25       |
+| c        | gcc     main.c -o out.gcc && ./out.gcc         |        2 / 25       |
+| c++      | g++     main.cpp -o out.g++ && ./out.g++       |        2 / 25       |
 | ruby     | ruby    main.rb                                |        1 / 25       |
 | rust     | rustc   main.rs -o out.rustc && ./out.rustc    |        1 / 25       |
-| sml      | polyc   main.sml -o out.polyc && ./out.polyc   |        1 / 25       |
 | bash     | bash    main.bash                              |        0 / 25       |
 | golang   | go run  main.go                                |        0 / 25       |
 | java     | javac   Main.java && java Main                 |        0 / 25       |

days/day-03/README.md

@@ -1,3 +1,79 @@
-# days/day-03
-## --- Part 1 ---
-## --- Part 2 ---
+# --- Day 3: Toboggan Trajectory ---
+
+With the toboggan login problems resolved, you set off toward the airport. While travel by toboggan might be easy, it's certainly not safe: there's very minimal steering and the area is covered in trees. You'll need to see which angles will take you near the fewest trees.
+
+Due to the local geology, trees in this area only grow on exact integer coordinates in a grid. You make a map (your puzzle input) of the open squares (.) and trees (#) you can see. For example:
+
+```
+..##.......
+#...#...#..
+.#....#..#.
+..#.#...#.#
+.#...##..#.
+..#.##.....
+.#.#.#....#
+.#........#
+#.##...#...
+#...##....#
+.#..#...#.#
+```
+
+These aren't the only trees, though; due to something you read about once involving arboreal genetics and biome stability, the same pattern repeats to the right many times:
+
+```
+..##.........##.........##.........##.........##.........##.......  --->
+#...#...#..#...#...#..#...#...#..#...#...#..#...#...#..#...#...#..
+.#....#..#..#....#..#..#....#..#..#....#..#..#....#..#..#....#..#.
+..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.#
+.#...##..#..#...##..#..#...##..#..#...##..#..#...##..#..#...##..#.
+..#.##.......#.##.......#.##.......#.##.......#.##.......#.##.....  --->
+.#.#.#....#.#.#.#....#.#.#.#....#.#.#.#....#.#.#.#....#.#.#.#....#
+.#........#.#........#.#........#.#........#.#........#.#........#
+#.##...#...#.##...#...#.##...#...#.##...#...#.##...#...#.##...#...
+#...##....##...##....##...##....##...##....##...##....##...##....#
+.#..#...#.#.#..#...#.#.#..#...#.#.#..#...#.#.#..#...#.#.#..#...#.#  --->
+```
+
+You start on the open square (.) in the top-left corner and need to reach the bottom (below the bottom-most row on your map).
+
+The toboggan can only follow a few specific slopes (you opted for a cheaper model that prefers rational numbers); start by counting all the trees you would encounter for the slope right 3, down 1:
+
+From your starting position at the top-left, check the position that is right 3 and down 1. Then, check the position that is right 3 and down 1 from there, and so on until you go past the bottom of the map.
+
+The locations you'd check in the above example are marked here with O where there was an open square and X where there was a tree:
+
+```
+..##.........##.........##.........##.........##.........##.......  --->
+#..O#...#..#...#...#..#...#...#..#...#...#..#...#...#..#...#...#..
+.#....X..#..#....#..#..#....#..#..#....#..#..#....#..#..#....#..#.
+..#.#...#O#..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.#
+.#...##..#..X...##..#..#...##..#..#...##..#..#...##..#..#...##..#.
+..#.##.......#.X#.......#.##.......#.##.......#.##.......#.##.....  --->
+.#.#.#....#.#.#.#.O..#.#.#.#....#.#.#.#....#.#.#.#....#.#.#.#....#
+.#........#.#........X.#........#.#........#.#........#.#........#
+#.##...#...#.##...#...#.X#...#...#.##...#...#.##...#...#.##...#...
+#...##....##...##....##...#X....##...##....##...##....##...##....#
+.#..#...#.#.#..#...#.#.#..#...X.#.#..#...#.#.#..#...#.#.#..#...#.#  --->
+```
+
+In this example, traversing the map using this slope would cause you to encounter 7 trees.
+
+Starting at the top-left corner of your map and following a slope of right 3 and down 1, how many trees would you encounter?
+
+## --- Part Two ---
+
+Time to check the rest of the slopes - you need to minimize the probability of a sudden arboreal stop, after all.
+
+Determine the number of trees you would encounter if, for each of the following slopes, you start at the top-left corner and traverse the map all the way to the bottom:
+
+```
+    Right 1, down 1.
+    Right 3, down 1. (This is the slope you already checked.)
+    Right 5, down 1.
+    Right 7, down 1.
+    Right 1, down 2.
+```
+
+In the above example, these slopes would find 2, 7, 3, 4, and 2 tree(s) respectively; multiplied together, these produce the answer 336.
+
+What do you get if you multiply together the number of trees encountered on each of the listed slopes?

days/day-03/solutions/.keep

@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <string.h>
+
+const int MAX_LINE = 100;
+const char TREE = '#';
+
+struct Toboggan {
+  int x;
+  int trees_hit;
+  const int right;
+  const int down;
+};
+
+// Declare a bunch of toboggans (sleighs)
+const int TOBOGGANS_SIZE = 5;
+struct Toboggan toboggans[5] = {
+  { .x = 0, .right = 3, .down = 1, .trees_hit = 0 },
+  { .x = 0, .right = 1, .down = 1, .trees_hit = 0 },
+  { .x = 0, .right = 5, .down = 1, .trees_hit = 0 },
+  { .x = 0, .right = 7, .down = 1, .trees_hit = 0 },
+  { .x = 0, .right = 1, .down = 2, .trees_hit = 0 },
+};
+
+int main() {
+  // Ignore start-line
+  char line[MAX_LINE];
+  fgets(line, MAX_LINE, stdin);
+  const int WRAP_WIDTH = strlen(line) - 1;
+
+  // Read line by line starting from line 1
+  int y = 1;
+  for (char line[MAX_LINE]; fgets(line, MAX_LINE, stdin); ++y) {
+
+    for (int i = 0; i < TOBOGGANS_SIZE; ++i) {
+      struct Toboggan* toboggan = &toboggans[i];
+
+      // Skip current line, for this specific toboggan, if...
+      if (y % toboggan->down != 0) {
+        continue;
+      }
+
+      toboggan->x = (toboggan->x + toboggan->right) % WRAP_WIDTH;
+      toboggan->trees_hit = toboggan->trees_hit + (line[toboggan->x] == TREE);
+    }
+  }
+
+  long int tree_product = 1;
+  for (int i = 0; i < TOBOGGANS_SIZE; ++i) {
+      tree_product = tree_product * toboggans[i].trees_hit;
+  }
+
+  printf("%d\n", toboggans[0].trees_hit);
+  printf("%ld\n", tree_product);
+
+  return 0;
+}

days/day-03/solutions/day03.c

@@ -6,6 +6,7 @@ D=$(dirname $(realpath $0))
 echo ""
 echo "--- Day 3: Counting trees ---"
 $D/../../languages/python.sh $D/input.txt $D/output.txt $D/solutions/day03.py
-$D/../../languages/sml.sh $D/input.txt $D/output.txt $D/solutions/day03.sml
+$D/../../languages/sml.sh    $D/input.txt $D/output.txt $D/solutions/day03.sml
 $D/../../languages/python.sh $D/input.txt $D/output.txt $D/solutions/python_klyve.py
+$D/../../languages/c.sh      $D/input.txt $D/output.txt $D/solutions/day03.c
 echo ""