Year 2024 Day 14

Author: maneatingape

README.md

@@ -85,6 +85,7 @@ Performance is reasonable even on older hardware, for example a 2011 MacBook Pro
 | 11 | [Plutonian Pebbles](https://adventofcode.com/2024/day/11) | [Source](src/year2024/day11.rs) | 248 |
 | 12 | [Garden Groups](https://adventofcode.com/2024/day/12) | [Source](src/year2024/day12.rs) | 289 |
 | 13 | [Claw Contraption](https://adventofcode.com/2024/day/13) | [Source](src/year2024/day13.rs) | 14 |
+| 14 | [Restroom Redoubt](https://adventofcode.com/2024/day/14) | [Source](src/year2024/day14.rs) | 1604 |
 
 ## 2023
 

benches/benchmark.rs

@@ -87,5 +87,6 @@ benchmark!(year2023
 );
 
 benchmark!(year2024
-    day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13
+    day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13,
+    day14
 );

src/lib.rs

@@ -67,5 +67,6 @@ library!(year2023 "Restore global snow production."
 );
 
 library!(year2024 "Locate the Chief Historian in time for the big Christmas sleigh launch."
-    day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13
+    day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13,
+    day14
 );

src/main.rs

@@ -139,5 +139,6 @@ run!(year2023
 );
 
 run!(year2024
-    day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13
+    day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13,
+    day14
 );

src/year2024/day14.rs

@@ -0,0 +1,69 @@
+//! # Restroom Redoubt
+//!
+//! For part one we jump straight to the final position by multiplying the velocity by 100.
+//! The image appears in part two when the positions of all robots is unqiue.
+use crate::util::grid::*;
+use crate::util::iter::*;
+use crate::util::parse::*;
+use crate::util::point::*;
+
+type Robot = [i32; 4];
+
+pub fn parse(input: &str) -> Vec<Robot> {
+    input.iter_signed().chunk::<4>() .collect()
+}
+
+pub fn part1(input: &[Robot]) -> i32 {
+    let mut q1 = 0;
+    let mut q2 = 0;
+    let mut q3 = 0;
+    let mut q4 = 0;
+
+    for [x, y, dx, dy] in input {
+        let x = (x + 100 * dx).rem_euclid(101);
+        let y = (y + 100 * dy).rem_euclid(103);
+
+        if x < 50 {
+            if y < 51 {
+                q1 += 1;
+            }
+            if y > 51 {
+                q2 += 1;
+            }
+        }
+        if x > 50 {
+            if y < 51 {
+                q3 += 1;
+            }
+            if y > 51 {
+                q4 += 1;
+            }
+        }
+    }
+
+    q1 * q2 * q3 * q4
+}
+
+pub fn part2(robots: &[Robot]) -> i32 {
+    let mut grid = Grid::new(101, 103, 0);
+    let mut time = 0;
+    let mut overlap = true;
+
+    while overlap {
+        time += 1;
+        overlap = false;
+
+        for [x, y, dx, dy] in robots {
+            let next = Point::new((x + dx * time).rem_euclid(101), (y + dy * time).rem_euclid(103));
+
+            if grid[next] == time {
+                overlap = true;
+                break;
+            }
+
+            grid[next] = time;
+        }
+    }
+
+    time
+}

tests/test.rs

@@ -80,5 +80,6 @@ test!(year2023
 );
 
 test!(year2024
-    day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13
+    day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13,
+    day14
 );

tests/year2024/day14.rs

@@ -0,0 +1,9 @@
+#[test]
+fn part1_test() {
+    // No test
+}
+
+#[test]
+fn part2_test() {
+    // No test
+}