using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Advent24
{
    internal class Day1
    {
        public Day1()
        {
            string fileData = System.IO.File.ReadAllText(@"..\..\..\inputd1.txt");
            var pairsArray = fileData.Split('\n');

            var list1 = new SortedList<Int32, Int32>(pairsArray.Length);
            var list2 = new SortedList<Int32, Int32>(pairsArray.Length);
            foreach (var pair in pairsArray)
            {
                if (System.String.IsNullOrEmpty(pair)) continue;
                // pairArray has 4 elements, and the middle two are blanks
                // because there are 3 spaces between the two numbers
                var pairArray = pair.Split(' ');
                Int32 myInteger = System.Convert.ToInt32(pairArray[0]);
                if (list1.TryGetValue(myInteger, out int value1)) list1[myInteger] = ++value1;
                else list1.Add(myInteger, 1);
                Console.WriteLine("{0:d} {1:d}", myInteger, list1[myInteger]);

                myInteger = System.Convert.ToInt32(pairArray[3]);
                if (list2.TryGetValue(myInteger, out int value2)) list2[myInteger] = ++value2;
                else list2.Add(myInteger, 1);
                Console.WriteLine("{0:d} {1:d}", myInteger, list2[myInteger]);
            }

            Int32 sumOfDifferences = 0;
            Int32 i = 0, j = 0;

            var list1Copy = new SortedList<Int32, Int32>(list1);
            var list2Copy = new SortedList<Int32, Int32>(list2);

            while (i < list1.Count && j < list2.Count)
            {
                Int32 value1 = list1.GetKeyAtIndex(i);
                Int32 value2 = list2.GetKeyAtIndex(j);

                if (value1 > value2) sumOfDifferences += (value1 - value2);
                else sumOfDifferences += (value2 - value1);

                list1[value1]--; list2[value2]--;

                if (list1[value1] == 0) i++;
                if (list2[value2] == 0) j++;
            }

            Console.WriteLine("{0:s} {1:d}", "Sum of differences = ", sumOfDifferences);

            i = 0; Int32 similarityScore = 0;
            while (i < list1Copy.Count)
            {
                Int32 value1 = list1Copy.GetKeyAtIndex(i);
                list2Copy.TryGetValue(value1, out Int32 numberOfAppearancesInList2);

                // default value of Int32 numberOfAppearancesInList2 is 0
                similarityScore += value1 * numberOfAppearancesInList2;

                list1Copy[value1]--;

                if (list1Copy[value1] == 0) i++;
            }

            Console.WriteLine("{0:s} {1:d}", "Similarity score = ", similarityScore);

            Console.ReadLine();
        }
    }
}