Project 11 - Greatest Product

Project11.cs

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

namespace Project11
{

    public class Point 
    {
        public int x;
        public int y;
        public override string ToString()
        {
            return string.Format("({0},{1})", y, x);
        }
    }

    // A sequence of four Points
    public class Segment : List<Point>
    {
        public override string ToString()
        {
            StringBuilder sb = new StringBuilder();
            foreach (Point pt in this)
            {
                sb.Append(pt.ToString());
                sb.Append("    ");
            }
            return sb.ToString();
        }
        public string ShowGridValues(int[,] grid)
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("[ ");
            foreach (Point pt in this)
            {
                sb.Append(grid[pt.x, pt.y]);
                sb.Append("    ");
            }
            sb.Append(" ]");
            return sb.ToString();
        }

    }


    // This is where the work gets done.
    public class Program
    {
        int[,] grid = new int[,] 
                    {{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}};




        List<Point> points = new List<Point>();
        Dictionary<string, List<Segment>> segments = new Dictionary<string, List<Segment>>();
        private Segment topSegment = new Segment();
        private int topProduct = 0;
        private int computations = 0;

        static void Main(string[] args)
        {
            new Program().Run();
        }

        public void Run()
        {
            DateTime start = DateTime.Now;

            ComputePoints();
            foreach (Point pt in points)
            {
                ComputeSegments(pt);
            }
            foreach (Point pt in points)
            {
                foreach (Segment seg in segments[pt.ToString()])
                {
                    int product = ComputeProduct(seg, grid);
                    if (product > topProduct)
                    {
                        topProduct = product;
                        topSegment = seg;
                    }
                }
            }

            DateTime end = DateTime.Now;
            Console.WriteLine("Segment {0} -  {1}   has total of {2}", topSegment, topSegment.ShowGridValues(grid), topProduct);
            Console.WriteLine("Performed {0} computations in {1} milliseconds.", computations, end.Subtract(start).TotalMilliseconds);
            Console.ReadLine();
        }

        public void ComputePoints()
        {
            for (int x = 0; x < 20; x++)
            {
                for (int y = 0; y < 20; y++)
                {
                    points.Add(new Point { x = x, y = y });
                }
            }
        }
        public void ComputeSegments(Point pt)
        {
            List<Segment> result = new List<Segment>();
            result.Add(ComputeUp(pt));
            result.Add(ComputeUpRight(pt));
            result.Add(ComputeRight(pt));
            result.Add(ComputeDownRight(pt));
            result.Add(ComputeDown(pt));
            result.Add(ComputeDownLeft(pt));
            result.Add(ComputeLeft(pt));
            result.Add(ComputeUpLeft(pt));
            segments[pt.ToString()] = result;
        }

        public int ComputeProduct(Segment seg, int[,] grid)
        {
            if (seg.Count != 4)
                return 0;

            int idx = 0;
            int[] vals = new int[4];
            foreach (Point pt in seg)
            {
                vals[idx++] = grid[pt.x, pt.y];
            }
            computations++;
            return vals[0] * vals[1] * vals[2] * vals[3];
        }

        public Segment ComputeUp(Point pt)
        {
            var result = new Segment();
            if (pt.y >= 3)
            {
                result.Add(new Point { x = pt.x, y = pt.y });
                result.Add(new Point { x = pt.x, y = pt.y - 1 });
                result.Add(new Point { x = pt.x, y = pt.y - 2 });
                result.Add(new Point { x = pt.x, y = pt.y - 3 });
            }
            return result;
        }
        public Segment ComputeUpRight(Point pt)
        {
            var result = new Segment();
            if (pt.y >= 3 && pt.x <= 16)
            {
                result.Add(new Point { x = pt.x, y = pt.y });
                result.Add(new Point { x = pt.x + 1, y = pt.y - 1 });
                result.Add(new Point { x = pt.x + 2, y = pt.y - 2 });
                result.Add(new Point { x = pt.x + 3, y = pt.y - 3 });
            }
            return result;
        }
        public Segment ComputeRight(Point pt)
        {
            var result = new Segment();
            if (pt.x <= 16)
            {
                result.Add(new Point { x = pt.x, y = pt.y });
                result.Add(new Point { x = pt.x + 1, y = pt.y });
                result.Add(new Point { x = pt.x + 2, y = pt.y });
                result.Add(new Point { x = pt.x + 3, y = pt.y });
            }
            return result;
        }
        public Segment ComputeDownRight(Point pt)
        {
            var result = new Segment();
            if (pt.x <= 16 && pt.y <= 16)
            {
                result.Add(new Point { x = pt.x, y = pt.y });
                result.Add(new Point { x = pt.x + 1, y = pt.y + 1 });
                result.Add(new Point { x = pt.x + 2, y = pt.y + 2 });
                result.Add(new Point { x = pt.x + 3, y = pt.y + 3 });
            }
            return result;
        }
        public Segment ComputeDown(Point pt)
        {
            var result = new Segment();
            if (pt.y <= 16)
            {
                result.Add(new Point { x = pt.x, y = pt.y });
                result.Add(new Point { x = pt.x, y = pt.y + 1 });
                result.Add(new Point { x = pt.x, y = pt.y + 2 });
                result.Add(new Point { x = pt.x, y = pt.y + 3 });
            }
            return result;
        }
        public Segment ComputeDownLeft(Point pt)
        {
            var result = new Segment();
            if (pt.x >= 3 && pt.y <= 16)
            {
                result.Add(new Point { x = pt.x, y = pt.y });
                result.Add(new Point { x = pt.x - 1, y = pt.y + 1 });
                result.Add(new Point { x = pt.x - 2, y = pt.y + 2 });
                result.Add(new Point { x = pt.x - 3, y = pt.y + 3 });
            }
            return result;
        }
        public Segment ComputeLeft(Point pt)
        {
            var result = new Segment();
            if (pt.x >= 3)
            {
                result.Add(new Point { x = pt.x, y = pt.y });
                result.Add(new Point { x = pt.x - 1, y = pt.y });
                result.Add(new Point { x = pt.x - 2, y = pt.y });
                result.Add(new Point { x = pt.x - 3, y = pt.y });
            }
            return result;
        }
        public Segment ComputeUpLeft(Point pt)
        {
            var result = new Segment();
            if (pt.x >= 3 && pt.y >= 3)
            {
                result.Add(new Point { x = pt.x, y = pt.y });
                result.Add(new Point { x = pt.x - 1, y = pt.y - 1 });
                result.Add(new Point { x = pt.x - 2, y = pt.y - 2 });
                result.Add(new Point { x = pt.x - 3, y = pt.y - 3 });
            }
            return result;
        }
    }
}