Very quick implementation for day 1

2021/src/day01.rs

@@ -1,9 +1,63 @@
+use std::io::BufRead;
+use std::io::BufReader;
 use std::io::Read;
 
-pub fn part1(_input: &mut dyn Read) -> String {
-    todo!()
+fn read_input(input: &mut dyn Read) -> Vec<u32> {
+    let reader = BufReader::new(input);
+
+    // TODO: optimize allocations out
+    reader
+        .lines()
+        .map(|l| l.unwrap().parse().unwrap())
+        .collect()
 }
 
-pub fn part2(_input: &mut dyn Read) -> String {
-    todo!()
+pub fn part1(input: &mut dyn Read) -> String {
+    let numbers = read_input(input);
+
+    numbers
+        .windows(2)
+        .filter(|w| w[1] > w[0])
+        .count()
+        .to_string()
+}
+
+pub fn part2(input: &mut dyn Read) -> String {
+    let numbers = read_input(input);
+
+    let mut last = None;
+
+    numbers
+        .windows(3)
+        .filter(|w| {
+            let sum: u32 = w.iter().sum();
+
+            let prev = last.replace(sum);
+
+            match prev {
+                Some(n) if n < sum => true,
+                _ => false,
+            }
+        })
+        .count()
+        .to_string()
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::test_implementation;
+
+    use super::*;
+
+    const SAMPLE: &[u8] = include_bytes!("samples/01.txt");
+
+    #[test]
+    fn sample_part1() {
+        test_implementation(part1, SAMPLE, 7);
+    }
+
+    #[test]
+    fn sample_part2() {
+        test_implementation(part2, SAMPLE, 5);
+    }
 }

2021/src/lib.rs

@@ -88,3 +88,10 @@ pub fn get_implementation(day: usize, part2: bool) -> Solution {
         }
     }
 }
+
+#[cfg(test)]
+fn test_implementation(solution: Solution, data: impl AsRef<[u8]>, answer: impl ToString) {
+    let result = solution(&mut data.as_ref());
+
+    assert_eq!(answer.to_string(), result);
+}

2021/src/samples/01.txt

@@ -0,0 +1,10 @@
+199
+200
+208
+210
+200
+207
+240
+269
+260
+263