Rust

   #[test]
    fn test_y2025_day5_part2() {
        let input = std::fs::read_to_string("input/2025/day_5.txt").unwrap();
        let (fresh, _) = input.split_once("\n\n").unwrap();
        let mut fresh = fresh
            .lines()
            .map(|l| {
                let (p1, p2) = l.split_once("-").unwrap();
                (p1.parse::<usize>().unwrap(), p2.parse::<usize>().unwrap())
            })
            .collect::<Vec<(usize, usize)>>();

        fresh.sort_by_key(|a| a.0);

        let mut non_overlapping = vec![*fresh.first().unwrap()];

        for range in fresh[1..].iter() {
            let last = *non_overlapping.last().unwrap();
            if range.0 > last.1 {
                // println!("Non overlapping: {range:?} -> {last:?}");
                non_overlapping.push((range.0, range.1));
                continue;
            }
            if range.0 <= last.1 && range.1 > last.1 {
                // println!("Overlapping: {range:?} -> {last:?}");
                let new_last = (last.0, range.1);
                non_overlapping.pop();
                non_overlapping.push(new_last);
                continue;
            }
            // println!("{range:?} is entirely within {last:?}");
        }

        let mut count = 0;
        for r in &non_overlapping {
            count += r.1 - r.0 + 1;
        }
        assert_eq!(count, 352556672963116);
        println!("{}", count);
    }

Took me way longer than it should have to work out pt2, got tripped up by a < instead of <=.