As the forklifts break through the wall, the Elves are delighted to discover that there was a cafeteria on the other side after all.

You can hear a commotion coming from the kitchen. "At this rate, we won't have any time left to put the wreaths up in the dining hall!" Resolute in your quest, you investigate.

Visit the website for the full story and full puzzle description.

namespace AdventOfCode.Y2025.Day05;

using System;
using System.Collections.Generic;
using System.Linq;

record Range(long start, long end);

[ProblemName("Cafeteria")]
class Solution : Solver {

    public object PartOne(string input) {
        var (ranges, nums) = Parse(input);
        return nums.Count(num => ranges.Any(range => range.start <= num && num <= range.end));
    }

    public object PartTwo(string input) {
        // Sort ranges by start so that potentionally overlapping ranges come after 
        // each other. Then walk the list and make them disjoint:
        var ranges = Parse(input).ranges.OrderBy(x => x.start).ToArray();
        for (var i = 0; i < ranges.Length - 1; i++) {
            if (ranges[i+1].start <= ranges[i].end) {
                var end = Math.Max(ranges[i].end, ranges[i + 1].end);
                ranges[i] = new Range(ranges[i].start, ranges[i+1].start - 1);
                ranges[i+1] = new Range(ranges[i+1].start, end);
            }
        }
        return ranges.Sum(range => range.end - range.start + 1);
    }

    (Range[] ranges, long[] nums) Parse(string input) {
        var blocks = input.Split("\n\n");
        var ranges = (
            from line in blocks[0].Split("\n")
            let limits = line.Split("-").Select(long.Parse).ToArray()
            select new Range(limits[0], limits[1])
        ).ToArray();

        var nums = blocks[1].Split("\n").Select(long.Parse).ToArray();
        return (ranges, nums);
    }
}

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