From 796138a9e48c25279670bbe3fc36ef3d08c986db Mon Sep 17 00:00:00 2001
From: Ben C <bwc9876@gmail.com>
Date: Fri, 5 Dec 2025 07:47:36 -0500
Subject: [PATCH] Day 5

---
 utils/src/range.rs                  | 17 ++++++++-
 years/2025/src/day_5.rs             | 56 +++++++++++++++++++++++++----
 years/2025/src/examples/day_5/1.txt | 11 ++++++
 years/2025/src/examples/day_5/2.txt | 11 ++++++
 4 files changed, 88 insertions(+), 7 deletions(-)

diff --git a/utils/src/range.rs b/utils/src/range.rs
index 0e842fe..de3f76f 100644
--- a/utils/src/range.rs
+++ b/utils/src/range.rs
@@ -51,7 +51,22 @@ impl<T: Copy + Clone + Debug + Ord> BetterRange<T> {
     /// ```
     ///
     pub fn contains_range(&self, other: &Self) -> bool {
-        self.start <= other.start && other.end < self.end
+        self.start <= other.start && other.end <= self.end
+    }
+
+    /// Merge this range with another. If the ranges do not intersect, [None] is returned.
+    pub fn merge(&self, other: &Self) -> Option<Self> {
+        if self.contains_range(other) {
+            Some(*self)
+        } else if other.contains_range(self) {
+            Some(*other)
+        } else if self.contains(&other.start) || self.end == other.start {
+            Some(Self::new(self.start, other.end))
+        } else if self.contains(&other.end) || other.end == self.start {
+            Some(Self::new(other.start, self.end))
+        } else {
+            None
+        }
     }
 
     /// Split the range at the given value.
diff --git a/years/2025/src/day_5.rs b/years/2025/src/day_5.rs
index a87ca56..98de929 100644
--- a/years/2025/src/day_5.rs
+++ b/years/2025/src/day_5.rs
@@ -1,17 +1,61 @@
-
 use advent_core::{Day, day_stuff, ex_for_day};
+use utils::range::BetterRange;
 
 pub struct Day5;
 
 impl Day for Day5 {
+    day_stuff!(5, "3", "14", (Vec<BetterRange<usize>>, Vec<usize>));
+
+    fn part_1((ranges, ids): Self::Input) -> Option<String> {
+        let ans = ids
+            .into_iter()
+            .filter(|id| ranges.iter().any(|range| range.contains(id)))
+            .count();
+
+        Some(ans.to_string())
+    }
+
+    fn part_2((mut ranges, _): Self::Input) -> Option<String> {
+        ranges.sort_by(|a, b| a.start.cmp(&b.start).then(a.end.cmp(&b.end)));
 
-    day_stuff!(5, "", "");
+        let mut new_ranges = Vec::with_capacity(ranges.len());
 
-    fn part_1(_input: Self::Input) -> Option<String> {
-        None
+        for range in ranges {
+            let mut merged = false;
+
+            for new_range in new_ranges.iter_mut() {
+                if let Some(merged_range) = range.merge(new_range) {
+                    merged = true;
+                    *new_range = merged_range;
+                    break;
+                }
+            }
+
+            if !merged {
+                new_ranges.push(range);
+            }
+        }
+
+        let ans = new_ranges
+            .into_iter()
+            .map(|range| range.end - range.start)
+            .sum::<usize>();
+
+        Some(ans.to_string())
     }
 
-    fn part_2(_input: Self::Input) -> Option<String> {
-        None
+    fn parse_input(input: &str) -> Self::Input {
+        let (ranges, ids) = input.split_once("\n\n").unwrap();
+
+        (
+            ranges
+                .lines()
+                .map(|l| {
+                    let (lower, upper) = l.split_once('-').unwrap();
+                    BetterRange::new(lower.parse().unwrap(), upper.parse::<usize>().unwrap() + 1)
+                })
+                .collect(),
+            ids.lines().map(|l| l.parse().unwrap()).collect(),
+        )
     }
 }
diff --git a/years/2025/src/examples/day_5/1.txt b/years/2025/src/examples/day_5/1.txt
index e69de29..2e9078d 100644
--- a/years/2025/src/examples/day_5/1.txt
+++ b/years/2025/src/examples/day_5/1.txt
@@ -0,0 +1,11 @@
+3-5
+10-14
+16-20
+12-18
+
+1
+5
+8
+11
+17
+32
diff --git a/years/2025/src/examples/day_5/2.txt b/years/2025/src/examples/day_5/2.txt
index e69de29..2e9078d 100644
--- a/years/2025/src/examples/day_5/2.txt
+++ b/years/2025/src/examples/day_5/2.txt
@@ -0,0 +1,11 @@
+3-5
+10-14
+16-20
+12-18
+
+1
+5
+8
+11
+17
+32
-- 
2.51.2