AoC 2021 Day 07

#load "xunit"
#load ".\AoCConnector"
#load ".\2dArrayExtensions"

async Task Main()
{

    RunTests();  // Call RunTests() or press Alt+Shift+T to initiate testing.

    var aoc = AoC.GetAOC(2021, 7);

    var answerA = SolveA(aoc.GetLines);
    await aoc.SubmitAnswer(Part.Part1, answerA);


    var answerB = SolveB(aoc.GetLines);
    await aoc.SubmitAnswer(Part.Part2, answerB.ToString().Dump());
}

public int SolveA(string[] lines) => Solve(lines, true);
public int SolveB(string[] lines) => Solve(lines, false);

public int Solve(string[] lines, bool v1)
{
    //parse the data
    var inputArray = lines[0].Split(',').Select(x => int.Parse(x)).ToArray();
    Dictionary<int, int> dicCache = new Dictionary<int, int>();

    int min = 0;
    int max = inputArray.Length - 1;
    while (min <= max)
    {
        int mid = (min + max) / 2;
        int midLeft = mid - ((mid - min) / 2);
        int midRight = mid + ((max - mid) / 2);

        int leftValue = GetValue(midLeft);
        int rightValue = GetValue(midRight);

        if (rightValue < leftValue)
        {
            min = midLeft;
        }
        else if (leftValue < rightValue)
        {
            max = midRight;
        }
        else
        {
            return GetValue(mid);
        }
    }
    throw new NotImplementedException();

    int GetValue(int target)
    {
        if (dicCache.TryGetValue(target, out var result) == false)
        {
            result = 0;
            for (int f = 0; f < inputArray.Length; f++)
            {
                var dist = Math.Abs(target - inputArray[f]);

                if(v1)
                    result += dist;
                else
                    result += dist * (dist + 1) / 2;
            }
            dicCache[target] = result;
        }
        return result;
    }
}


#region private::Tests

string[] TestData = new []
{
"16,1,2,0,4,2,7,1,2,14"
};

[Fact] void Test_SolvaA() => Assert.Equal(37, SolveA(TestData));
[Fact] void Test_SolveB() => Assert.Equal(168, SolveB(TestData));

#endregion