1 files changed, 56 insertions, 0 deletions
diff --git a/08/src/part-1.rs b/08/src/part-1.rs
new file mode 100644
index 0000000..bdfb409
--- /dev/null
+++ b/08/src/part-1.rs
@@ -0,0 +1,56 @@
+mod stuff;
+
+use std::collections::{HashMap};
+
+use crate::stuff::{ascii_to_u64, is_all_ascii_ws, read_helper, Direction, Node};
+
+pub const START: Node = [b'A', b'A', b'A'];
+pub const FINISH: Node = [b'Z', b'Z', b'Z'];
+
+
+
+fn main() {
+    let mut stdin = std::io::stdin().lock();
+
+    let mut buf: Vec<u8> = Vec::new();
+
+    let num_bytes = read_helper(&mut stdin, &mut buf, b'\n').expect("IO error");
+    if num_bytes == 0 { panic!("Malformed input"); }    
+    let instructions: Vec<Direction> = (& buf).into_iter()
+        .map(|& c| Direction::try_from(c).expect("Malformed input"))
+        .collect();
+
+    let num_bytes = read_helper(&mut stdin, &mut buf, b'\n').expect("IO error");
+    assert!(is_all_ascii_ws(& buf));
+
+    let mut nodes: HashMap<Node, (Node, Node)> = HashMap::new();
+    
+    loop {
+        let num_bytes = read_helper(&mut stdin, &mut buf, b'=').expect("IO error");
+        if num_bytes == 0 { break; }
+        let node: Node = core::array::from_fn(|i| buf[i]);
+        
+        let num_bytes = read_helper(&mut stdin, &mut buf, b',').expect("IO error");
+        if num_bytes == 0 { panic!("Malformed input"); }
+        let node_l: Node = core::array::from_fn(|i| buf[2+i]);
+
+        let num_bytes = read_helper(&mut stdin, &mut buf, b'\n').expect("IO error");
+        if num_bytes == 0 { panic!("Malformed input"); }
+        let node_r: Node = core::array::from_fn(|i| buf[1+i]);        
+        
+        nodes.insert(node, (node_l, node_r));
+    }
+
+    let mut node: Node = START;
+    for (i, instruction) in instructions.into_iter().cycle().enumerate() {
+        if node == FINISH {
+            println!("{}", i);
+            break;
+        }
+        let (left, right) = nodes.get(& node).expect("Non-existent node");
+        match instruction {
+            Direction::L => { node = *left; },
+            Direction::R => { node = *right; }
+        }
+    }
+}