using System;

using System.Diagnostics;

using System.Text;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        InsertSpaces1();

        InsertSpaces2();

        InsertSpaces3();

        InsertSpaces4();

    }

​

    private static void InsertSpaces1()

    {

        Stopwatch w = new Stopwatch();

        w.Start();

        string text = " ( ((abc ) def)ghi)";

        text = Regex.Replace(text.Replace("(", " ( ").Replace(")", " ) "), @"[ ]{2,}", @" ");

        Console.WriteLine(text);

        w.Stop();

        Console.WriteLine(w.Elapsed);

    }

​

    private static void InsertSpaces2()

    {

        Stopwatch w = new Stopwatch();

        w.Start();

        string text = " ( ((abc ) def )ghi)";

        text = Regex.Replace(text.Replace(" ", String.Empty), "\\w+|[()]", "$0 ");

        Console.WriteLine(text);

        w.Stop();

        Console.WriteLine(w.Elapsed);

    }

​

    private static void InsertSpaces3()

    {

        Stopwatch w = new Stopwatch();

        w.Start();

        StringBuilder text = new StringBuilder("( ((abc ) def )ghi)");

        for (int i = 0; i < text.Length; i++) 

        {

            if (

                (text[i] == '(' && ((i - 1 >= 0 && text[i - 1] != ' ') || i == 0)) ||

                (text[i] == ')' && ((i - 1 >= 0 && text[i - 1] != ' ') || i == 0))

               )

            {

                text.Insert(i, ' ');

            } 

            else if (

                     (text[i] == '(' && (i + 1 < text.Length && text[i + 1] != ' ')) ||

                     (text[i] == ')' && (i + 1 < text.Length && text[i + 1] != ' '))

                    )

            {

                text.Insert(i + 1, ' ');

            }

            else if (

                     (text[i] == '(' && (i + 1 == text.Length)) ||

                     (text[i] == ')' && (i + 1 == text.Length))

                    )

            {

                text.Append(" ");

            }

        }

        Console.WriteLine(text);

        w.Stop();

        Console.WriteLine(w.Elapsed);

    }

​

    private static void InsertSpaces4()

    {

        Stopwatch w = new Stopwatch();

        w.Start();

        string text = "( ((abc ) def )ghi)";

        for (int i = 0; i < text.Length; i++) 

        {

            if (

                (text[i] == '(' && ((i - 1 >= 0 && text[i - 1] != ' ') || i == 0)) ||

                (text[i] == ')' && ((i - 1 >= 0 && text[i - 1] != ' ') || i == 0))

               )

            {

                text = text.Insert(i, " ");

            } 

            else if (

                     (text[i] == '(' && (i + 1 < text.Length && text[i + 1] != ' ')) ||

                     (text[i] == ')' && (i + 1 < text.Length && text[i + 1] != ' '))

                    )

            {

                text = text.Insert(i + 1, " ");

            }

            else if (

                     (text[i] == '(' && (i + 1 == text.Length)) ||

                     (text[i] == ')' && (i + 1 == text.Length))

                    )

            {

                text += " ";

            }

        }

        Console.WriteLine(text);

        w.Stop();

        Console.WriteLine(w.Elapsed);

    }

}