Euler 11

Euler11.cs

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Math;
using static System.Console;

namespace Euler11
{
    class Program
    {
        struct Grid
        {
            public int Width;
            public int Height;
            public IReadOnlyList<int> Data;

            public int this[int x, int y] => (x < Width && y < Height) ? Data[y * Width + x] : 0;

            public Grid(int width, int height, IList<int> data)
            {
                Width = width;
                Height = height;
                Data = new List<int>(data).AsReadOnly();
            }

            public int GetHorizontal(int x, int y)
            {
                return this[x, y]
                     * this[x + 1, y]
                     * this[x + 2, y]
                     * this[x + 3, y];
            }

            public int GetVertical(int x, int y)
            {
                return this[x, y]
                     * this[x, y + 1]
                     * this[x, y + 2]
                     * this[x, y + 3];
            }

            public int GetDownRight(int x, int y)
            {
                return this[x, y]
                     * this[x + 1, y + 1]
                     * this[x + 2, y + 2]
                     * this[x + 3, y + 3];
            }

            public int GetDownLeft(int x, int y)
            {
                return this[x, y]
                     * this[x - 1, y + 1]
                     * this[x - 2, y + 2]
                     * this[x - 3, y + 3];
            }
        }

        static void Main(string[] args)
        {
            var stringGrid = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65 52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80 24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50 32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70 67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21 24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72 21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95 78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92 16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57 86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58 19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40 04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66 88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69 04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36 20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16 20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54 01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48";
            var gridData = stringGrid.Split(' ').Select(x => Convert.ToInt32(x)).ToArray();
            var grid = new Grid(20, 20, gridData);

            var max = 0;

            for (var y = 0; y < grid.Height; y++)
            {
                for (var x = 0; x < grid.Width; x++)
                {
                    max = Max(max, grid.GetHorizontal(x, y));
                    max = Max(max, grid.GetVertical(x, y));
                    max = Max(max, grid.GetDownRight(x, y));
                    max = Max(max, grid.GetDownLeft(x, y));
                }
            }

            WriteLine($"The largest product is { max }");
        }
    }
}