feat: completed day 3

ankjevel · ankjevel · commit 697506337527 · 2020-12-05T20:13:44.000+01:00
diff --git a/README.md b/README.md
@@ -5,7 +5,7 @@
 
 - [Day 1](https://github.com/ankjevel/adventofcode/tree/2020/day_01) 🌟 🌟
 - [Day 2](https://github.com/ankjevel/adventofcode/tree/2020/day_02) 🌟 🌟
-- [Day 3](#)
+- [Day 3](https://github.com/ankjevel/adventofcode/tree/2020/day_03) 🌟 🌟
 - [Day 4](#)
 - [Day 5](#)
 - [Day 6](#)
diff --git a/day_03/Cargo.toml b/day_03/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "day_03"
+version = "0.1.0"
+authors = ["Dennis Pettersson <mail@dennispettersson.se>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/day_03/src/lib.rs b/day_03/src/lib.rs
@@ -0,0 +1,50 @@
+pub mod part_01;
+pub mod part_02;
+
+#[derive(Clone, Copy, Eq, PartialEq, Hash, Debug)]
+pub enum Square {
+    Open,
+    Tree,
+}
+
+use Square::{Open, Tree};
+
+pub fn parse_input(input: &str) -> Vec<Vec<Square>> {
+    input
+        .lines()
+        .map(|string| string.trim())
+        .filter(|string| !string.is_empty())
+        .into_iter()
+        .map(|string| {
+            string
+                .chars()
+                .into_iter()
+                .map(|square| if square == '.' { Open } else { Tree })
+                .collect()
+        })
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        parse_input,
+        Square::{Open, Tree},
+    };
+
+    const EXAMPLE_DATA: &'static str = "
+        ..##.......
+        #...#...#..
+    ";
+
+    #[test]
+    fn it_can_parse_input() {
+        assert_eq!(
+            parse_input(&EXAMPLE_DATA),
+            vec![
+                vec![Open, Open, Tree, Tree, Open, Open, Open, Open, Open, Open, Open],
+                vec![Tree, Open, Open, Open, Tree, Open, Open, Open, Tree, Open, Open]
+            ]
+        )
+    }
+}
diff --git a/day_03/src/main.rs b/day_03/src/main.rs
@@ -0,0 +1,12 @@
+use std::io::Result;
+
+use day_03::{parse_input, part_01::main as part_01, part_02::main as part_02};
+
+fn main() -> Result<()> {
+    let input = parse_input(include_str!("../../input/day_03"));
+
+    println!("part_01: {:?}", part_01(&input).unwrap());
+    println!("part_02: {:?}", part_02(&input).unwrap());
+
+    Ok(())
+}
diff --git a/day_03/src/part_01.rs b/day_03/src/part_01.rs
@@ -0,0 +1,45 @@
+use std::io::Result;
+
+use crate::{Square, Square::Tree};
+
+pub fn main(input: &Vec<Vec<Square>>) -> Result<usize> {
+    let max = input.get(0).unwrap().len();
+    let mut index = 0;
+    Ok(input
+        .into_iter()
+        .map(|row| {
+            let square = row.get(index).unwrap();
+
+            index = (index + 3) % max;
+
+            square.to_owned()
+        })
+        .filter(|square| square == &Tree)
+        .count())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::parse_input;
+
+    use super::main;
+
+    const EXAMPLE_DATA: &'static str = "
+        ..##.......
+        #...#...#..
+        .#....#..#.
+        ..#.#...#.#
+        .#...##..#.
+        ..#.##.....
+        .#.#.#....#
+        .#........#
+        #.##...#...
+        #...##....#
+        .#..#...#.#
+    ";
+
+    #[test]
+    fn it_gets_the_example_correct() {
+        assert_eq!(main(&parse_input(EXAMPLE_DATA)).unwrap(), 7);
+    }
+}
diff --git a/day_03/src/part_02.rs b/day_03/src/part_02.rs
@@ -0,0 +1,48 @@
+use std::io::Result;
+
+use crate::{Square, Square::Tree};
+
+pub fn main(input: &Vec<Vec<Square>>) -> Result<usize> {
+    let max = input.get(0).unwrap().len();
+    Ok(vec![(1, 1), (3, 1), (5, 1), (7, 1), (1, 2)]
+        .into_iter()
+        .fold(1, |count, (right, down)| {
+            let mut index = right.to_owned();
+            let trees = (down..input.len())
+                .step_by(down)
+                .map(|i| {
+                    let square = input.get(i).unwrap().get(index).unwrap();
+                    index = (index + right) % max;
+                    square.to_owned()
+                })
+                .filter(|square| square == &Tree)
+                .count();
+            count * trees
+        }))
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::parse_input;
+
+    use super::main;
+
+    const EXAMPLE_DATA: &'static str = "
+        ..##.......
+        #...#...#..
+        .#....#..#.
+        ..#.#...#.#
+        .#...##..#.
+        ..#.##.....
+        .#.#.#....#
+        .#........#
+        #.##...#...
+        #...##....#
+        .#..#...#.#
+    ";
+
+    #[test]
+    fn it_gets_the_example_correct() {
+        assert_eq!(main(&parse_input(EXAMPLE_DATA)).unwrap(), 336);
+    }
+}
diff --git a/input/day_03 b/input/day_03
