Add 9 first days

5-binary_boarding/src/main.rs

@@ -0,0 +1,82 @@
+use std::convert::TryFrom;
+use std::str::FromStr;
+use anyhow::Result;
+
+struct Plane {
+    cols: usize,
+    rows: usize,
+}
+const my_plane: Plane = Plane { cols: 8, rows: 128};
+
+#[derive(Debug, thiserror::Error, PartialEq)]
+enum ParseError {
+    #[error("Expected {0}")]
+    Expected(&'static str),
+}
+
+#[derive(Debug, PartialEq)]
+struct Seat {
+    col: usize,
+    row: usize,
+}
+
+impl FromStr for Seat {
+    type Err = ParseError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if s.len() != 10 { return Err(ParseError::Expected("10-char string")) }
+
+        // split_at not supposed to fail as we are only working with ASCII chars here
+        let s_bit = s
+            .replace("F", "0")
+            .replace("B", "1")
+            .replace("R","1")
+            .replace("L", "0")
+            .chars()
+            .collect::<String>();
+        let (rowcode, colcode) = s_bit.split_at(7);
+        Ok(Self {
+            row: usize::from_str_radix(&rowcode, 2).unwrap(),
+            col: usize::from_str_radix(&colcode, 2).unwrap(),
+        })
+    }
+}
+
+impl Seat {
+    fn seat_id(&self) -> usize {
+        8 * self.row + self.col
+    }
+}
+
+fn main() {
+    let input = include_str!("../data/input.txt");
+    let mut seat_ids: Vec<usize> = input.lines().map(|l| Seat::from_str(l).unwrap().seat_id()).collect();
+    seat_ids.sort();
+    println!("Max seat id: {:?}", seat_ids.iter().max());
+    let banana = seat_ids
+        .windows(2)
+        .flat_map(<&[usize;2]>::try_from) // Because windows() makes no promise on slice size 
+        .find(|[a, b]| *b == *a + 2);
+    eprintln!("banana = {:#?}", banana);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    const AOC_INPUT: &str = "FBFBBFFRLR";
+    #[test]
+    fn test_build_seat() {
+        assert_eq!(
+            Seat::from_str(AOC_INPUT),
+            Ok(Seat { row: 44, col: 5 })
+        );
+    }
+
+    #[test]
+    fn test_seat_id() {
+        assert_eq!(
+            Seat::from_str(AOC_INPUT).unwrap().seat_id(),
+            357
+        );
+    }
+}