CircularSectorCalculator.cs

using System;
using System.Linq;

namespace PracticeAlgorithmCSharp
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            Solution();
        }

        private struct Vector
        {
            public double x;
            public double y;

            public Vector Normalized()
            {
                double length = Length();
                return new Vector
                {
                    x = x / length,
                    y = y / length
                };
            }

            public double Length()
            {
                return Math.Sqrt(SqrLength());
            }

            public double SqrLength()
            {
                return Math.Abs(x * x + y * y);
            }

            public override string ToString()
            {
                return $"{x}, {y}";
            }

            public static Vector operator -(Vector a, Vector b)
                => new Vector { x = a.x - b.x, y = a.y - b.y };
        }

        public static void Solution()
        {
            var line = Console.ReadLine().Split(' ').Select((c) => int.Parse(c)).ToArray();
            Vector mousePos = new Vector() { x = line[0], y = line[1] };
            int r = line[2];
            int d = line[3];
            var targets = new Vector[]
            {
                new Vector { x = 0, y = 1 },
                new Vector { x = -1, y = 1 },
                new Vector { x = 1, y = 0 },
                new Vector { x = -1, y = 0 },
                new Vector { x = 0, y = -1 },
                new Vector { x = -1, y = -1 },
                new Vector { x = -2, y = 2 },
                new Vector { x = -mousePos.x, y = -mousePos.y }
            };

            double rad = DegToRad(d);

            int result = 0;
            foreach (var target in targets)
            {
                if (target.SqrLength() > r * r)
                {
                    continue;
                }

                Vector a = mousePos.Normalized();
                Vector b = target.Normalized();
                double dot = Dot(a, b);
                double cos = Math.Cos(rad);
                if (dot > cos)
                {
                    ++result;
                    Console.WriteLine(target);
                }
            }

            Console.WriteLine(result);
        }

        private static double RadToDeg(double rad)
        {
            return (rad * 180.0 / Math.PI);
        }

        private static double DegToRad(double deg)
        {
            return (deg * Math.PI / 180.0);
        }

        private static double Dot(Vector a, Vector b)
        {
            return (a.x * b.x) + (a.y * b.y);
        }
    }
}