day 8 part 1

2021/src/day8.rs

@@ -0,0 +1,112 @@
+use std::str::FromStr;
+
+use color_eyre::eyre;
+use eyre::eyre;
+
+use crate::lib::{ParseLines, IterExt};
+
+
+#[derive(Debug)]
+enum Segment {
+    A = 1,
+    B = 2,
+    C = 4,
+    D = 8,
+    E = 16,
+    F = 32,
+    G = 64, // wheee!
+}
+use Segment::*;
+
+impl Segment {
+    fn from_char(c: char) -> eyre::Result<Self> {
+        match c {
+            'a' => Ok(A),
+            'b' => Ok(B),
+            'c' => Ok(C),
+            'd' => Ok(D),
+            'e' => Ok(E),
+            'f' => Ok(F),
+            'g' => Ok(G),
+            _ => Err(eyre!("Invalid character for segment: {}", c)),
+        }
+    }
+}
+
+
+#[derive(Default, Debug)]
+struct SegmentSet {
+    data: u8,
+    len: u8,
+}
+
+impl SegmentSet {
+    fn contains(&self, segment: Segment) -> bool {
+        self.data & (segment as u8) > 0
+    }
+
+    fn insert(&mut self, segment: Segment) {
+        self.data |= segment as u8;
+        self.len += 1;
+    }
+
+    fn remove(&mut self, segment: Segment) {
+        self.data ^= segment as u8;
+        self.len -= 1
+    }
+
+    fn len(&self) -> u8 {
+        self.len
+    }
+}
+
+impl FromStr for SegmentSet {
+    type Err = eyre::Report;
+    fn from_str(s: &str) -> eyre::Result<Self> {
+        let mut set = Self::default();
+        for c in s.chars() {
+            set.insert(Segment::from_char(c)?);
+        }
+        Ok(set)
+    }
+}
+
+
+#[derive(Default, Debug)]
+struct Screen {
+    patterns: [SegmentSet; 10],
+    output: [SegmentSet; 4],
+}
+
+impl FromStr for Screen {
+    type Err = eyre::Report;
+    fn from_str(s: &str) -> eyre::Result<Self> {
+        let mut screen = Screen::default();
+        let (patterns, output) = s.split(" | ").take_pair()?;
+        
+        for (i, patt) in patterns.split(' ').enumerate() {
+            screen.patterns[i] = patt.parse::<SegmentSet>()?;
+        }
+        for (i, out) in output.split(' ').enumerate() {
+            screen.output[i] = out.parse::<SegmentSet>()?;
+        }
+        Ok(screen)
+    }
+}
+
+
+fn part1(screens: &[Screen]) -> usize {
+    screens.iter()
+        .flat_map(|d| d.output.iter())
+        .filter(|s| matches!(s.len(), 2|3|4|7))
+        .count()
+}
+
+
+pub fn run(data: &str) -> eyre::Result<(usize, usize)> {
+    let screens = data
+        .parse_lines::<Screen>()
+        .collect::<Result<Vec<_>, _>>()?;
+
+    Ok((part1(&screens), 0))
+}

2021/src/main.rs

@@ -4,14 +4,14 @@ use color_eyre::eyre;
 
 mod lib;
 use lib::load;
-mod day7;
+mod day8;
 
 
 fn main() -> eyre::Result<()> {
-    let data = load("data/07.txt")?;
+    let data = load("data/08.txt")?;
 
     let start = Instant::now();
-    let (one, two) = day7::run(&data)?;
+    let (one, two) = day8::run(&data)?;
     let (dur, unit) = format_ns(start.elapsed().as_nanos());
 
     let precision = 2.0 - dur.log10().floor();