using System;

using System.Linq;

​

namespace AoCDay2

{

    public class Program

    {

        public static void Main()

        {

            string input =

                "1,0,0,3,1,1,2,3,1,3,4,3,1,5,0,3,2,1,10,19,1,6,19,23,1,13,23,27,1,6,27,31,1,31,10,35,1,35,6,39,1,39,13,43,2,10,43,47,1,47,6,51,2,6,51,55,1,5,55,59,2,13,59,63,2,63,9,67,1,5,67,71,2,13,71,75,1,75,5,79,1,10,79,83,2,6,83,87,2,13,87,91,1,9,91,95,1,9,95,99,2,99,9,103,1,5,103,107,2,9,107,111,1,5,111,115,1,115,2,119,1,9,119,0,99,2,0,14,0";

            int[] inputs = input.Split(',').Select(int.Parse).ToArray();

​

            if(TryFindNounAndVerb(inputs, 19690720, out int noun, out int verb))

                Console.WriteLine($"Noun: {noun} || Verb: {verb}");

            else

                Console.WriteLine("No fitting noun and verb found.");

        }

​

        public static bool TryFindNounAndVerb(int[] numbers, int goal, out int noun, out int verb)

        {

            var initialNumbers = new int[numbers.Length];

            Array.Copy(numbers, initialNumbers, numbers.Length);

            verb = 0;

            noun = 0;

            for(noun = 0; noun <= 99 ; noun++)

            {

                for(verb = 0; verb <= 99 ; verb++)

                {

                    Array.Copy(initialNumbers, numbers, numbers.Length);

                    numbers[1] = noun;

                    numbers[2] = verb;

                    if(TryCalculateResult(numbers, out int result) && result == goal)

                    {

                        return true;

                    }

                }

            }

​

            return false;

        }

​

        public static bool TryCalculateResult(int[] numbers, out int result)

        {

            for(int i = 0; i < numbers.Length; i += 4)

            {

                var operation = numbers[i];

                result = numbers[0];

                if(operation == 99)

                {

                    return true;

                }

​

                // Check if we can access all the position positions.

                if(i + 3 >= numbers.Length)

                    return false;

​

                var firstPosition = numbers[i + 1];

                var secondPosition = numbers[i + 2];

                var targetPosition = numbers[i + 3];

                // Check if we can access all the actual positions

                if(firstPosition >= numbers.Length || secondPosition >= numbers.Length || targetPosition >= numbers.Length)

                    return false;

                var firstNumber = numbers[firstPosition];

                var secondNumber = numbers[secondPosition];

​

                switch(operation)

                {

                    case 1:

                        numbers[targetPosition] = firstNumber + secondNumber;

                        break;

                    case 2:

                        numbers[targetPosition] = firstNumber * secondNumber;

                        break;

                }

            }

            result = numbers[0];

            return true;

        }

    }

}