Day 14

Author: UnderscoreTud

README.md

@@ -41,9 +41,10 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | [Day 10](./src/bin/10.rs) | `96.9µs` | `97.3µs` |
 | [Day 11](./src/bin/11.rs) | `218.3µs` | `11.2ms` |
 | [Day 12](./src/bin/12.rs) | `3.0ms` | `2.8ms` |
-| [Day 13](./src/bin/13.rs) | `246.8µs` | `198.9µs` |
+| [Day 13](./src/bin/13.rs) | `248.3µs` | `204.6µs` |
+| [Day 14](./src/bin/14.rs) | `46.3µs` | `46.2ms` |
 
-**Total: 193.77ms**
+**Total: 240.03ms**
 <!--- benchmarking table --->
 
 ---

data/examples/14.txt

@@ -0,0 +1,12 @@
+p=0,4 v=3,-3
+p=6,3 v=-1,-3
+p=10,3 v=-1,2
+p=2,0 v=2,-1
+p=0,0 v=1,3
+p=3,0 v=-2,-2
+p=7,6 v=-1,-3
+p=3,0 v=-1,-2
+p=9,3 v=2,3
+p=7,3 v=-1,2
+p=2,4 v=2,-3
+p=9,5 v=-3,-3

src/bin/14.rs

@@ -0,0 +1,105 @@
+use itertools::Itertools;
+
+advent_of_code::solution!(14);
+
+#[cfg(not(test))]
+const WIDTH: u8 = 101;
+#[cfg(not(test))]
+const HEIGHT: u8 = 103;
+
+#[cfg(test)]
+const WIDTH: u8 = 11;
+#[cfg(test)]
+const HEIGHT: u8 = 7;
+
+#[derive(Debug)]
+struct Robot {
+    position: (isize, isize),
+    velocity: (isize, isize),
+}
+
+impl Robot {
+    fn parse(input: &str) -> Robot {
+        let pos_x = &input[input.find('=').unwrap() + 1..input.find(',').unwrap()];
+        let pos_y = &input[input.find(',').unwrap() + 1..input.find(' ').unwrap()];
+
+        let vel_x = &input[input.rfind('=').unwrap() + 1..input.rfind(',').unwrap()];
+        let vel_y = &input[input.rfind(',').unwrap() + 1..];
+
+        Robot {
+            position: (pos_x.parse().unwrap(), pos_y.parse().unwrap()),
+            velocity: (vel_x.parse().unwrap(), vel_y.parse().unwrap()),
+        }
+    }
+
+    fn simulate(&mut self, seconds: isize) {
+        let (offset_x, offset_y) = (self.velocity.0 * seconds, self.velocity.1 * seconds);
+        let new_position = (self.position.0 + offset_x, self.position.1 + offset_y);
+        self.position = (new_position.0.rem_euclid(WIDTH as isize), new_position.1.rem_euclid(HEIGHT as isize));
+    }
+
+    fn get_quadrant(&self) -> Option<u8> {
+        let (center_column, center_row) = (WIDTH as isize / 2, HEIGHT as isize / 2);
+        if self.position.0 < center_column && self.position.1 < center_row {
+            Some(0)
+        } else if self.position.0 > center_column && self.position.1 < center_row {
+            Some(1)
+        } else if self.position.0 < center_column && self.position.1 > center_row {
+            Some(2)
+        } else if self.position.0 > center_column && self.position.1 > center_row {
+            Some(3)
+        } else {
+            None
+        }
+    }
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let mut quadrants = [0; 4];
+    input.lines()
+        .map(Robot::parse)
+        .map(|mut robot| {
+            robot.simulate(100);
+            robot
+        })
+        .filter_map(|robot| robot.get_quadrant())
+        .for_each(|quadrant| quadrants[quadrant as usize] += 1);
+    Some(quadrants.iter().product())
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let (mut lowest_safety_factor, mut seconds_passed) = (u32::MAX, 0);
+    let mut robots = input.lines().map(Robot::parse).collect_vec();
+    for second in 1..=WIDTH as u16 * HEIGHT as u16 {
+        let mut quadrants = [0; 4];
+        robots.iter_mut()
+            .map(|robot| {
+                robot.simulate(1);
+                robot
+            })
+            .filter_map(|robot| robot.get_quadrant())
+            .for_each(|quadrant| quadrants[quadrant as usize] += 1);
+        let safety_factor = quadrants.iter().product();
+        if safety_factor < lowest_safety_factor {
+            lowest_safety_factor = safety_factor;
+            seconds_passed = second;
+        }
+    }
+    Some(seconds_passed as u32)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(12));
+    }
+
+    #[test]
+    fn test_part_two() {
+        // Cannot test part two
+    }
+}