day 05

src/bin/05.rs

@@ -0,0 +1,87 @@
+advent_of_code::solution!(5);
+use itertools::Itertools;
+
+pub fn part_one(input: &str) -> Option<u64> {
+    let lists = input.split("\n\n").collect_vec();
+    let ranges = lists[0]
+        .lines()
+        .map(|line| {
+            let (start, end) = line.split_once('-').unwrap();
+            // println!("Parsed range: {}-{}", start, end);
+            (start.parse::<u64>().unwrap(), end.parse::<u64>().unwrap())
+        })
+        .collect_vec();
+    let ids = lists[1].lines().map(|line| line.parse::<u64>().unwrap()).collect_vec();
+
+    // println!("{ranges:?}");
+    // println!("{ids:?}");
+    let mut fresh_item_count = 0;
+
+    for id in ids {
+        for (start, end) in &ranges {
+            if id >= *start && id <= *end {
+                // println!("ID {id} is in range {start}-{end}");
+                fresh_item_count += 1;
+                break;
+            }
+        }
+    }
+
+    Some(fresh_item_count)
+}
+
+pub fn part_two(input: &str) -> Option<u64> {
+    let lists = input.split("\n\n").collect_vec();
+    let mut ranges = lists[0]
+        .lines()
+        .map(|line| {
+            let (start, end) = line.split_once('-').unwrap();
+            // println!("Parsed range: {}-{}", start, end);
+            (start.parse::<u64>().unwrap(), end.parse::<u64>().unwrap())
+        })
+        .collect_vec();
+    ranges.sort_by(|a, b| if a.0 != b.0 {
+            a.0.cmp(&b.0)
+        } else {
+            a.1.cmp(&b.1)
+        });
+    // println!("{ranges:?}");
+
+    let mut i = 0;
+    while i < ranges.len() - 1 {
+        let (start_a, end_a) = ranges[i];
+        let (start_b, end_b) = ranges[i + 1];
+        if end_a >= start_b {
+            let new_end = end_a.max(end_b);
+            ranges[i] = (start_a, new_end);
+            ranges.remove(i + 1);
+            // println!("Merged to: {:?}", ranges[i]);
+        }
+        else {
+            i += 1;
+        }
+    }
+    // println!("{ranges:?}");
+
+    let total_count = ranges.iter().map(|(start, end)| end - start + 1).sum::<u64>();
+    // sort and merge ranges
+
+    Some(total_count)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(3));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(14));
+    }
+}