2023 day 11.

Author: nerdatmath

2023/10/src/puzzle.rs

@@ -45,12 +45,12 @@ fn find_starting_direction(grid: &Grid, starting_position: Position) -> Option<D
     use Pipe::*;
     Some(match patch_pipe(grid, starting_position)? {
         Ground => unreachable!(),
-        NorthSouth => N,
+        NorthSouth => S,
         EastWest => E,
         NorthEast => N,
-        NorthWest => N,
+        NorthWest => W,
         SouthWest => S,
-        SouthEast => S,
+        SouthEast => E,
         Start => unreachable!(),
     })
 }

2023/11/.gitignore

@@ -0,0 +1 @@
+/target

2023/11/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "y2023d11"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+game-grid.workspace = true
+position.workspace = true
+parse-display.workspace = true

2023/11/data/example1

@@ -0,0 +1,10 @@
+...#......
+.......#..
+#.........
+..........
+......#...
+.#........
+.........#
+..........
+.......#..
+#...#.....

2023/11/data/input

@@ -0,0 +1,5 @@
+#[cfg(test)]
+pub const EXAMPLE1: &'static str = include_str!("../data/example1");
+
+#[allow(unused)]
+pub const INPUT: &'static str = include_str!("../data/input");

2023/11/src/data.rs

@@ -0,0 +1,32 @@
+pub fn distance_sum(counts: impl IntoIterator<Item = u64>, factor: u64) -> u64 {
+    let mut pos: u64 = 0;
+    let mut sum: u64 = 0;
+    let mut sum_of_pos: u64 = 0;
+    let mut count: u64 = 0;
+    for c in counts {
+        if c == 0 {
+            pos += factor;
+            continue;
+        }
+        pos += 1;
+        sum_of_pos += pos * c;
+        sum += pos * (count * 2 + c - 1) * c;
+        count += c;
+    }
+    sum - sum_of_pos * (count - 1)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_distance_sum_1() {
+        assert_eq!(distance_sum([2, 1, 0, 1], 2), 13);
+    }
+
+    #[test]
+    fn test_distance_sum_2() {
+        assert_eq!(distance_sum([1, 0, 1, 2], 2), 13);
+    }
+}

2023/11/src/distance_sum.rs

@@ -0,0 +1,11 @@
+mod data;
+mod distance_sum;
+mod part1;
+mod part2;
+mod puzzle;
+
+fn main() {
+    use data::INPUT;
+    println!("Part 1: {}", part1::run(INPUT));
+    println!("Part 2: {}", part2::run(INPUT));
+}

2023/11/src/main.rs

@@ -0,0 +1,17 @@
+use crate::puzzle::Puzzle;
+
+pub fn run(input: &str) -> u64 {
+    let puzzle: Puzzle = input.parse().expect("parse failed");
+    puzzle.distance_sum_2d(2)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::data::EXAMPLE1;
+
+    #[test]
+    fn test1() {
+        assert_eq!(run(EXAMPLE1), 374);
+    }
+}

2023/11/src/part1/mod.rs

@@ -0,0 +1,26 @@
+use crate::puzzle::Puzzle;
+
+fn run_with_factor(input: &str, factor: u64) -> u64 {
+    let puzzle: Puzzle = input.parse().expect("parse failed");
+    puzzle.distance_sum_2d(factor)
+}
+
+pub fn run(input: &str) -> u64 {
+    run_with_factor(input, 1000000)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::data::EXAMPLE1;
+
+    #[test]
+    fn test1() {
+        assert_eq!(run_with_factor(EXAMPLE1, 10), 1030);
+    }
+
+    #[test]
+    fn test2() {
+        assert_eq!(run_with_factor(EXAMPLE1, 100), 8410);
+    }
+}