day 15 part 1

cleanup

cleanup

src/day09.rs

@@ -64,7 +64,7 @@ fn part2(input: &str) -> RiddleResult {
         } else {
             free.insert(head, l);
         }
-        head += l as usize;
+        head += l;
     }
     for file in files.iter_mut().rev() {
         let (start_index, length, _file_id) = *file;
@@ -73,7 +73,7 @@ fn part2(input: &str) -> RiddleResult {
             .take_while(|f| *f.0 < start_index)
             .find(|f| *f.1 >= length);
 
-        if let Some((&free_start, &free_length)) = found.clone() {
+        if let Some((&free_start, &free_length)) = found {
             free.remove(&free_start);
             free.insert(start_index, length);
             file.0 = free_start;

src/day14.rs

@@ -2,16 +2,17 @@ use std::{
     collections::HashSet,
     fs::read_to_string,
     io::{self, BufRead},
-    ops::Sub,
 };
 
 use itertools::Itertools;
 
+use crate::utils::grid::Grid;
+
 pub fn day_main() {
     let input = read_to_string("input/day14.txt").unwrap();
     let input = input.trim();
     println!(" part1: {}", part1(input));
-    // println!(" part2: {}", part2(input));
+    println!(" part2: {}", part2(input));
 }
 
 type RiddleResult = usize;
@@ -77,22 +78,27 @@ fn part2(input: &str) -> RiddleResult {
         if seen.contains(&robots) {
             panic!("Loop after {second} rounds, but no christmas tree!");
         }
+        let mut grid: Grid<u8> = Grid::from_default(101, 103);
         seen.insert(robots.clone());
         robots.iter_mut().for_each(|((px, py), (vx, vy))| {
             *px = (*px + width + *vx) % width;
             *py = (*py + height + *vy) % height;
+            grid[(*px, *py)] += 1;
+            if let Some(v) = grid.get_mut((*px + 1, *py)) {
+                *v += 1
+            }
+            if let Some(v) = grid.get_mut((*px - 1, *py)) {
+                *v += 1
+            }
+            if let Some(v) = grid.get_mut((*px, *py + 1)) {
+                *v += 1
+            }
+            if let Some(v) = grid.get_mut((*px, *py - 1)) {
+                *v += 1
+            }
         });
 
-        if robots
+        if robots.iter().filter(|(s, _)| grid[*s] > 1).count() > robots.len() * 70 / 100 {
-            .iter()
-            .filter(|(s, _)| {
-                robots
-                    .iter()
-                    .any(|(t, _)| t != s && (t.0.sub(s.0).abs() + t.1.sub(s.1).abs()) <= 2)
-            })
-            .count()
-            > robots.len() * 70 / 100
-        {
             printr(&robots, width, height);
             println!("after {} seconds. Press enter to continue or type 'merry christmas' if you can spot a tree!", second + 1); //+1 because we look at it after they have changed
             let stdin = io::stdin();
@@ -128,8 +134,6 @@ fn printr(robots: &[Robot], width: i64, height: i64) {
 mod test {
     use crate::day14::solve_part1;
 
-    use super::part2;
-
     const TEST_INPUT: &str = r"p=0,4 v=3,-3
 p=6,3 v=-1,-3
 p=10,3 v=-1,2
@@ -148,9 +152,4 @@ p=9,5 v=-3,-3
     fn test1() {
         assert_eq!(solve_part1(TEST_INPUT, 100, 11, 7), 12);
     }
-
-    #[test]
-    fn test2() {
-        assert_eq!(part2(TEST_INPUT), 0);
-    }
 }

src/day15.rs

@@ -0,0 +1,75 @@
+use std::fs::read_to_string;
+
+use crate::utils::grid::Grid;
+
+pub fn day_main() {
+    let input = read_to_string("input/day15.txt").unwrap();
+    let input = input.trim();
+    println!(" part1: {}", part1(input));
+    println!(" part2: {}", part2(input));
+}
+
+type RiddleResult = i64;
+
+fn part1(input: &str) -> RiddleResult {
+    let (grid, movements) = input.split_once("\n\n").unwrap();
+    let mut grid = Grid::parse(grid);
+    let mut robot = grid.entries().find(|(_r, c)| **c == '@').unwrap().0;
+    let directions = |d| match d {
+        '^' => (0, -1),
+        'v' => (0, 1),
+        '<' => (-1, 0),
+        '>' => (1, 0),
+        _ => panic!(),
+    };
+    for m in movements.chars().filter(|c| *c != '\n') {
+        let dir = directions(m);
+        let space = (1..)
+            .map(|i| (robot.0 + i * dir.0, robot.1 + i * dir.1))
+            .take_while(|p| grid.get(*p).is_some() && (grid[*p] == '.' || grid[*p] == 'O'))
+            .find(|p| grid[*p] == '.');
+        if let Some(p) = space {
+            if (p.0 - robot.0).abs() + (p.1 - robot.1).abs() > 1 {
+                // this means: the free spot is not a direct neighbor of the robot, i.e. there are boxes
+                grid[p] = 'O';
+            }
+            grid[robot] = '.';
+            robot = (robot.0 + dir.0, robot.1 + dir.1);
+            grid[robot] = '@';
+        }
+    }
+    grid.entries()
+        .filter(|(_, c)| **c == 'O')
+        .map(|((x, y), _)| y * 100 + x)
+        .sum()
+}
+
+fn part2(_input: &str) -> RiddleResult {
+    0
+}
+
+#[cfg(test)]
+mod test {
+    use super::{part1, part2};
+
+    const TEST_INPUT: &str = r"########
+#..O.O.#
+##@.O..#
+#...O..#
+#.#.O..#
+#...O..#
+#......#
+########
+
+<^^>>>vv<v>>v<<";
+
+    #[test]
+    fn test1() {
+        assert_eq!(part1(TEST_INPUT), 2028);
+    }
+
+    #[test]
+    fn test2() {
+        assert_eq!(part2(TEST_INPUT), 0);
+    }
+}

src/lib.rs

@@ -12,5 +12,6 @@ pub mod day11;
 pub mod day12;
 pub mod day13;
 pub mod day14;
+pub mod day15;
 // PLACEHOLDER
 pub mod utils;

src/main.rs

@@ -19,6 +19,7 @@ fn main() {
         (12, day12::day_main),
         (13, day13::day_main),
         (14, day14::day_main),
+        (15, day15::day_main),
         // PLACEHOLDER
     ]);
     let day: Option<u8> = args().nth(1).and_then(|a| a.parse().ok());

src/utils/grid.rs

@@ -99,6 +99,21 @@ impl<T> Grid<T> {
     }
 }
 
+impl<T> Grid<T>
+where
+    T: Default,
+{
+    pub fn from_default(width: i64, height: i64) -> Grid<T> {
+        let mut content: Vec<T> = Vec::with_capacity((width * height) as usize);
+        content.resize_with((width * height) as usize, Default::default);
+        Grid {
+            content_width: width,
+            content_height: height,
+            content,
+        }
+    }
+}
+
 impl Grid<char> {
     pub fn parse(input: &str) -> Grid<char> {
         let content_width = input.lines().next().unwrap().len();