Day 05

Author: m0lson84

README.md

@@ -215,7 +215,8 @@ By default, `cargo time` does not write to the readme. In order to do so, append
 | [Day 2](./src/bin/02.rs) | `27.5ms`  | `117.3ms` |
 | [Day 3](./src/bin/03.rs) | `34.8µs`  | `58.8µs`  |
 | [Day 4](./src/bin/04.rs) | `123.5µs` |  `4.0ms`  |
+| [Day 5](./src/bin/05.rs) | `90.8µs`  | `28.2µs`  |
 
-**Total: 149.11ms**
+**Total: 149.23ms**
 
 <!--- benchmarking table --->

data/examples/05.txt

@@ -0,0 +1,12 @@
+3-5
+10-14
+16-20
+12-18
+
+1
+5
+8
+11
+17
+32
+

src/bin/05.rs

@@ -0,0 +1,101 @@
+advent_of_code::solution!(5);
+
+type Range = (u64, u64);
+
+pub fn part_one(input: &str) -> Option<u64> {
+    let (ranges, ids) = parse_input(input)?;
+
+    let count = ids.iter().filter(|&&id| is_fresh(id, &ranges)).count();
+
+    Some(count as u64)
+}
+
+pub fn part_two(input: &str) -> Option<u64> {
+    let (ranges, _) = parse_input(input)?;
+    let merged = merge_ranges(ranges);
+
+    let count: u64 = merged.iter().map(|(start, end)| end - start + 1).sum();
+
+    Some(count)
+}
+
+fn parse_input(input: &str) -> Option<(Vec<Range>, Vec<u64>)> {
+    let parts: Vec<&str> = input.split("\n\n").collect();
+    if parts.len() < 2 {
+        return None;
+    }
+
+    let ranges = get_ranges(parts[0]);
+    let ids = get_ids(parts[1]);
+
+    Some((ranges, ids))
+}
+
+fn get_ranges(section: &str) -> Vec<Range> {
+    section
+        .lines()
+        .filter_map(|line| {
+            let nums: Vec<&str> = line.split('-').collect();
+            if nums.len() == 2 {
+                let start = nums[0].parse().ok()?;
+                let end = nums[1].parse().ok()?;
+                Some((start, end))
+            } else {
+                None
+            }
+        })
+        .collect()
+}
+
+fn get_ids(section: &str) -> Vec<u64> {
+    section
+        .lines()
+        .filter(|line| !line.is_empty())
+        .filter_map(|line| line.parse().ok())
+        .collect()
+}
+
+fn is_fresh(id: u64, ranges: &[Range]) -> bool {
+    ranges.iter().any(|&(start, end)| id >= start && id <= end)
+}
+
+fn merge_ranges(ranges: Vec<Range>) -> Vec<Range> {
+    if ranges.is_empty() {
+        return Vec::new();
+    }
+
+    let mut sorted = ranges;
+    sorted.sort_by_key(|&(start, _)| start);
+
+    let mut merged = vec![sorted[0]];
+
+    for &(start, end) in &sorted[1..] {
+        let last_idx = merged.len() - 1;
+        let (last_start, last_end) = merged[last_idx];
+
+        if start <= last_end + 1 {
+            merged[last_idx] = (last_start, last_end.max(end));
+        } else {
+            merged.push((start, end));
+        }
+    }
+
+    merged
+}
+
+#[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));
+    }
+}