using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Diagnostics;

namespace rvip_6
{
    public class Matrix
    {
        private readonly double[,] data;
        public int Size { get; }

        public Matrix(int size)
        {
            Size = size;
            data = new double[size, size];
            FillRandom();
        }

        public Matrix(double[,] data)
        {
            this.data = data;
            Size = data.GetLength(0);
        }

        public double GetElement(int row, int col)
        {
            return data[row, col];
        }

        public void SetElement(int row, int col, double value)
        {
            data[row, col] = value;
        }

        private void FillRandom()
        {
            Random random = new Random();
            for (int i = 0; i < Size; i++)
            {
                for (int j = 0; j < Size; j++)
                {
                    data[i, j] = random.NextDouble() * 10; // Заполняем случайными числами (0 - 10)
                }
            }
        }

        public double DeterminantSequential()
        {
            if (Size == 1)
                return data[0, 0];

            if (Size == 2)
                return data[0, 0] * data[1, 1] - data[0, 1] * data[1, 0];

            double det = 0;
            for (int j = 0; j < Size; j++)
            {
                det += (j % 2 == 0 ? 1 : -1) * data[0, j] * GetSubMatrix(0, j).DeterminantSequential();
            }
            return det;
        }

        private Matrix GetSubMatrix(int rowToRemove, int colToRemove)
        {
            double[,] subMatrix = new double[Size - 1, Size - 1];
            int subRow = 0;
            for (int row = 0; row < Size; row++)
            {
                if (row == rowToRemove)
                    continue;

                int subCol = 0;
                for (int col = 0; col < Size; col++)
                {
                    if (col == colToRemove)
                        continue;
                    subMatrix[subRow, subCol] = data[row, col];
                    subCol++;
                }
                subRow++;
            }
            return new Matrix(subMatrix);
        }

        public double DeterminantParallel(int numThreads)
        {
            if (Size == 1)
                return data[0, 0];

            if (Size == 2)
                return data[0, 0] * data[1, 1] - data[0, 1] * data[1, 0];

            double det = 0;
            var results = new double[Size];
            var tasks = new Task[Size];

            for (int j = 0; j < Size; j++)
            {
                int currentJ = j;
                tasks[j] = Task.Run(() =>
                {
                    results[currentJ] = (currentJ % 2 == 0 ? 1 : -1) * data[0, currentJ] * GetSubMatrix(0, currentJ).DeterminantParallel(numThreads);
                });
            }

            Task.WaitAll(tasks);
            for (int i = 0; i < results.Length; i++)
            {
                det += results[i];
            }
            return det;
        }

        public override string ToString()
        {
            string result = "";
            for (int i = 0; i < Size; i++)
            {
                for (int j = 0; j < Size; j++)
                {
                    result += data[i, j] + " ";
                }
                result += "\n";
            }
            return result;
        }
    }
}