clean up project

- modularized code into individual day modules
- moved utilities into utils module
- added unit testing

src/day01.rs

@@ -0,0 +1,33 @@
+use crate::utils;
+use anyhow::Result;
+
+fn count_incrementing_windows(window: usize, v: &[i64]) -> usize {
+    v[window..].iter().zip(v).filter(|(b, a)| b > a).count()
+}
+
+pub(crate) fn run() -> Result<(usize, usize)> {
+    let data = utils::read_i64s("data/day01.txt")?;
+    Ok((
+        count_incrementing_windows(1, &data),
+        count_incrementing_windows(3, &data),
+    ))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_example() {
+        let data = utils::read_i64s("data/day01-test.txt").unwrap();
+        assert_eq!(count_incrementing_windows(1, &data), 7);
+        assert_eq!(count_incrementing_windows(3, &data), 5);
+    }
+
+    #[test]
+    fn test_my_data() {
+        let data = utils::read_i64s("data/day01.txt").unwrap();
+        assert_eq!(count_incrementing_windows(1, &data), 1298);
+        assert_eq!(count_incrementing_windows(3, &data), 1248);
+    }
+}