day8 part1

day08/src/main.rs

@@ -0,0 +1,43 @@
+use std::{fs, collections::{HashMap, VecDeque}};
+
+fn main() {
+    let input = fs::read_to_string("input.txt").unwrap();
+    let input: Vec<_> = input.split("\n\n").collect();
+    let (directions, nodes) = (input[0], input[1]);
+    let directions: Vec<_> = directions.chars().map(|char| {
+        match char {
+            'L' => Direction::Left,
+            'R' => Direction::Right,
+            _ => panic!("Invalid direction!")
+        }
+    }).collect();
+
+    let nodes: HashMap<&str, (&str, &str)> = nodes.split('\n')
+        .map(|line| {
+            let line = line.split('=').map(|x| x.trim()).collect::<Vec<_>>();
+            let children: Vec<_> = line[1].trim_matches(|c| c == '(' || c == ')').split(", ").collect();
+            (line[0], (children[0], children[1]))
+        }).collect();
+
+    let mut cur_node = "AAA";
+    let mut step_queue = VecDeque::from(directions);
+    let mut step_count = 0;
+
+    while cur_node != "ZZZ" {
+        step_count += 1;
+        let cur_step = step_queue.pop_front().unwrap();
+        match cur_step {
+            Direction::Left => cur_node = nodes[cur_node].0,
+            Direction::Right => cur_node = nodes[cur_node].1,
+        }
+        step_queue.push_back(cur_step);
+    }
+
+    println!("{:?}", step_count);
+}
+
+#[derive(Debug)]
+enum Direction {
+    Left,
+    Right
+}