Add solution for "Day 7: Laboratories", part 1 and 2

src/solvers/laboratories.rs

@@ -0,0 +1,45 @@
+use crate::solvers::Solver;
+use memchr::{memchr, memchr_iter};
+use std::io::BufRead;
+
+pub struct Laboratories {}
+
+impl Laboratories {
+    const START_CHAR: u8 = b'S';
+    const SPLITTER_CHAR: u8 = b'^';
+
+    fn start_beam(line: &str) -> Vec<u64> {
+        let mut beams = vec![0; line.len()];
+        if let Some(s) = memchr(Self::START_CHAR, line.as_bytes()) {
+            beams[s] = 1;
+        }
+        beams
+    }
+
+    fn split_beams(line: &str, mut beams: Vec<u64>, mut splits: u64) -> (Vec<u64>, u64) {
+        for s in memchr_iter(Self::SPLITTER_CHAR, line.as_bytes()) {
+            if beams[s] > 0 {
+                splits += 1;
+                beams[s - 1] += beams[s];
+                beams[s + 1] += beams[s];
+                beams[s] = 0;
+            }
+        }
+        (beams, splits)
+    }
+}
+
+impl Solver for Laboratories {
+    const PUZZLE_INDEX: u8 = 7;
+    const PUZZLE_NAME: &'static str = "Laboratories";
+
+    fn process_data<R: BufRead>(&self, mut reader: R) -> (u64, u64) {
+        let line = reader.by_ref().lines().next().unwrap().unwrap();
+        let mut beams = Self::start_beam(&line);
+        let mut splits = 0;
+        for line in reader.lines().map_while(Result::ok) {
+            (beams, splits) = Self::split_beams(&line, beams, splits);
+        }
+        (splits, beams.iter().sum())
+    }
+}