DailyProgrammer Challenge #227e Solution (Square Spirals)

c-spiral.cs

using System;
using System.Linq;

namespace ChallengeSpiral
{
    class Program
    {
        static long ToPoint(long x, long y, long s)
        {
            if(x <= y)
            {
                if(x <= s - y + 1)
                {
                    long p = s + 1 - 2 * x;
                    return p * p + 1 + y - x;
                } else
                {
                    long p = 2 * y - s;
                    return p * p + x - y;
                }
            }
            else
            {
                if (x <= s - y + 1)
                {
                    long p = s + 1 - 2 * y;
                    return p * p + y + 1 - x;
                }
                else
                {
                    long p = 2 * x - s - 2;
                    return p * p + x - y;
                }
            }
        }

        static Tuple<long, long> ToLocation(long p, long s)
        {
            long sq = (long)Math.Ceiling(Math.Sqrt(p));
            long offset = p - sq * sq + 2 * sq - 2, center = (s + 1) / 2;
            long parity = (1 - (sq % 2) * 2);
            return new Tuple<long, long>(
                (sq / 2 - Math.Max(0, offset - sq + 1)) * parity + center,
                ((sq - 1) / 2 - Math.Min(offset, sq - 1)) * parity + center);
        }

        static void Main(string[] args)
        {
            Console.Write("Grid size: ");
            long gridSize = Convert.ToInt64(Console.ReadLine());
            if (gridSize % 2 == 1)
            {
                Console.WriteLine("Grid size must be even.");
            }
            else
            {
                Console.Write("Input: ");
                long[] inputs = Console.ReadLine().Split(' ').Select(s => Convert.ToInt64(s)).ToArray();

                if (inputs.Length == 1) // Point to location
                {
                    var location = ToLocation(inputs[0], gridSize);
                    Console.WriteLine("Location of Point {0} is ({1}, {2}).",
                        inputs[0],
                        location.Item1, location.Item2);
                }
                else if (inputs.Length == 2) // location to Point
                {
                    Console.WriteLine("Point corresponding to location ({0}, {1}) is {2}.",
                        inputs[0], inputs[1],
                        ToPoint(inputs[0], inputs[1], gridSize));
                }
                else
                {
                    Console.WriteLine("Malformed input.");
                }
                Console.ReadKey();
            }
        }
    }
}