day 8 part 1

2 files changed, 75 insertions, 0 deletions

diff --git a/src/bin/2023/day8.rs b/src/bin/2023/day8.rs
new file mode 100644
index 0000000..5b43ee5
--- /dev/null
+++ b/src/bin/2023/day8.rs
@@ -0,0 +1,73 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+
+use advent_of_code::prelude::*;
+
+#[derive(Clone, Copy)]
+enum Direction {
+    Left,
+    Right,
+}
+
+pub struct Network {
+    directions: Vec<Direction>,
+    graph: HashMap<String, (String, String)>,
+}
+
+pub fn parse(fh: File) -> Result<Network> {
+    let mut lines = parse::raw_lines(fh);
+    let directions = lines.next().unwrap();
+    lines.next().unwrap();
+    Ok(Network {
+        directions: directions
+            .chars()
+            .map(|c| {
+                if c == 'L' {
+                    Direction::Left
+                } else {
+                    Direction::Right
+                }
+            })
+            .collect(),
+        graph: lines
+            .map(|line| {
+                let cap = regex_captures!(r"(\w+) = \((\w+), (\w+)\)", &line)
+                    .unwrap();
+                (cap[1].to_string(), (cap[2].to_string(), cap[3].to_string()))
+            })
+            .collect(),
+    })
+}
+
+pub fn part1(network: Network) -> Result<i64> {
+    let mut vertex = "AAA".to_string();
+    let mut distance = 0;
+
+    while vertex != "ZZZ" {
+        let next = network.graph[&vertex].clone();
+        vertex = match network.directions[distance % network.directions.len()]
+        {
+            Direction::Left => next.0,
+            Direction::Right => next.1,
+        };
+        distance += 1;
+    }
+
+    Ok(distance.try_into().unwrap())
+}
+
+pub fn part2(network: Network) -> Result<i64> {
+    todo!()
+}
+
+#[test]
+fn test() {
+    assert_eq!(
+        part1(parse(parse::data(2023, 8).unwrap()).unwrap()).unwrap(),
+        11309
+    );
+    assert_eq!(
+        part2(parse(parse::data(2023, 8).unwrap()).unwrap()).unwrap(),
+        0
+    );
+}
diff --git a/src/bin/2023/main.rs b/src/bin/2023/main.rs
index 228cd57..569886c 100644
--- a/src/bin/2023/main.rs
+++ b/src/bin/2023/main.rs
@@ -18,6 +18,7 @@ mod day4;
 mod day5;
 mod day6;
 mod day7;
+mod day8;
 // NEXT MOD
 
 #[paw::main]
@@ -31,6 +32,7 @@ fn main(opt: Opt) -> Result<()> {
         5 => advent_of_code::day!(2023, opt.day, opt.puzzle, day5),
         6 => advent_of_code::day!(2023, opt.day, opt.puzzle, day6),
         7 => advent_of_code::day!(2023, opt.day, opt.puzzle, day7),
+        8 => advent_of_code::day!(2023, opt.day, opt.puzzle, day8),
         // NEXT PART
         _ => panic!("unknown day {}", opt.day),
     }