2025/day-05: Solve part 2

2025/rust/day-05/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day-05"
+version = "0.1.0"

2025/rust/day-05/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day-05"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

2025/rust/day-05/src/main.rs

@@ -0,0 +1,124 @@
+use std::fs;
+
+struct Range {
+    start: u64,
+    end: u64,
+}
+
+impl Range {
+    fn new(start: u64, end: u64) -> Self {
+        Range { start, end }
+    }
+
+    fn contains(&self, num: u64) -> bool {
+        num >= self.start && num <= self.end
+    }
+
+    fn overlaps(&self, other: &Range) -> bool {
+        self.contains(other.start) || self.contains(other.end)
+    }
+
+    fn merge_with(&mut self, overlap: &Range) {
+        if overlap.start < self.start {
+            self.start = overlap.start;
+        }
+        if overlap.end > self.end {
+            self.end = overlap.end;
+        }
+    }
+
+    fn length(&self) -> u64 {
+        self.end - self.start + 1
+    }
+}
+
+fn main() {
+    let (ranges, available_ids) = parse_input(&fs::read_to_string("../../inputs/05.txt").unwrap());
+    let ranges = merge_overlapping_ranges(ranges);
+
+    println!(
+        "Number of available IDs in ranges: {}",
+        count_available_ids_in_ranges(available_ids, &ranges)
+    );
+    println!("Number of IDs in ranges: {}", count_ids_in_ranges(&ranges));
+}
+
+fn parse_input(contents: &str) -> (Vec<Range>, Vec<u64>) {
+    let (ranges, available_ids) = contents.trim().split_once("\n\n").unwrap();
+
+    let ranges: Vec<Range> = ranges
+        .lines()
+        .map(|line| line.split_once("-").unwrap())
+        .map(|(start, end)| Range::new(start.parse().unwrap(), end.parse().unwrap()))
+        .collect();
+    let available_ids: Vec<u64> = available_ids
+        .lines()
+        .map(|line| line.parse().unwrap())
+        .collect();
+
+    (ranges, available_ids)
+}
+
+fn merge_overlapping_ranges(mut ranges: Vec<Range>) -> Vec<Range> {
+    ranges.sort_by_key(|range| range.start);
+
+    let mut compressed_ranges = vec![ranges.remove(0)];
+
+    for range in ranges {
+        let previous = compressed_ranges.last_mut().unwrap();
+
+        if previous.overlaps(&range) {
+            previous.merge_with(&range);
+        } else {
+            compressed_ranges.push(range);
+        }
+    }
+
+    compressed_ranges
+}
+
+fn count_available_ids_in_ranges(available_ids: Vec<u64>, ranges: &[Range]) -> usize {
+    available_ids
+        .iter()
+        .filter(|id| ranges.iter().any(|range| range.contains(**id)))
+        .count()
+}
+
+fn count_ids_in_ranges(ranges: &[Range]) -> u64 {
+    ranges.iter().map(|range| range.length()).sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT: &str = "
+3-5
+10-14
+16-20
+12-18
+
+1
+5
+8
+11
+17
+32
+";
+
+    #[test]
+    fn test_part1() {
+        let (ranges, available_ids) = parse_input(TEST_INPUT);
+        let ranges = merge_overlapping_ranges(ranges);
+
+        assert_eq!(count_available_ids_in_ranges(available_ids, &ranges), 3);
+    }
+
+    #[test]
+    fn test_part2() {
+        let (ranges, _) = parse_input(TEST_INPUT);
+        let ranges = merge_overlapping_ranges(merge_overlapping_ranges(ranges));
+
+        assert_eq!(count_ids_in_ranges(&ranges), 14);
+    }
+}

flake.lock

@@ -3,10 +3,10 @@
     "inputs": {
       "flake": false,
       "locked": {
-        "lastModified": 1764840758,
-        "narHash": "sha256-GTN8SBnhvv6t2oDS1H85xcYAhafy8mpUQWSrCErhtgw=",
+        "lastModified": 1764926544,
+        "narHash": "sha256-xIkgV9KrBel6Qwy673iMmmggFGZ9Zz93Hd/lGhRyHRM=",
         "ref": "refs/heads/main",
-        "rev": "415a59297c64d0448d22975ca5ad3d8ef064c9f0",
+        "rev": "27de1eaccb499f25dca8f3505b4c4f42a8e35514",
         "shallow": true,
         "type": "git",
         "url": "ssh://git@github.com/SebastianStork/advent-of-code-inputs.git"