C# Fundamentals - 02. NumberArray - MidExam 30.06.2020 Group 1

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;

namespace _02._NumberArray
{
    class NumberArray
    {
        static void Main(string[] args)
        {
            List<int> numbers = Console.ReadLine()
                                .Split()
                                .Select(int.Parse)
                                .ToList();

            string command = Console.ReadLine();
            while (command != "End")
            {
                string[] currentCommands = command.Split();
                string instruction = currentCommands[0];

                if (instruction == "Switch")
                {
                    int index = int.Parse(currentCommands[1]);

                    if (0 <= index && index < numbers.Count)
                    {
                        int replace = numbers[index];

                        int result = replace * -1;

                        numbers.RemoveAt(index);
                        numbers.Insert(index, result);
                    }

                    command = Console.ReadLine();
                    continue;
                }

                else if (instruction == "Change")
                {
                    int index = int.Parse(currentCommands[1]);
                    int value = int.Parse(currentCommands[2]);

                    if (0 <= index && index < numbers.Count)
                    {
                        numbers.RemoveAt(index);
                        numbers.Insert(index, value);
                    }

                    command = Console.ReadLine();
                    continue;
                }

                else if (instruction == "Sum")
                {
                    string options = currentCommands[1];

                    if (options == "Negative")
                    {
                        int sum = 0;

                        for (int i = 0; i < numbers.Count; i++)
                        {
                            if (numbers[i] < 0)
                            {
                                sum += numbers[i];
                            }
                        }
                        Console.WriteLine(sum);
                    }

                    else if (options == "Positive")
                    {
                        int sum = 0;


                        for (int i = 0; i < numbers.Count; i++)
                        {
                            if (0 < numbers[i])
                            {
                            sum += numbers[i];

                            }
                        }

                        Console.WriteLine(sum);
                    }

                    else if (options == "All")
                    {
                        Console.WriteLine(numbers.Sum());
                    }

                    command = Console.ReadLine();
                    continue;
                }
            }

            for (int i = 0; i < numbers.Count; i++)
            {
                if (0 <= numbers[i])
                {
                    Console.Write($"{numbers[i]} ");
                }
            }
        }
    }
}