# How to find all the different combinations of opening and closing brackets from the given number k using C#?

CsharpServer Side ProgrammingProgramming

Create a backtrack function that updates the current string if open brackets are less than n or close bracket are less than open bracket. When the length of current string becomes equal to 2*n, add it to the combination result array. It could be simply tracked by keeping the number of { } placed . We can start an opening bracket if we still have one left to place. And we can start a closing bracket if it would not exceed the number of opening brackets.

## Example

Live Demo

using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
namespace ConsoleApplication{
public class BackTracking{
public void Brackets(){
char[] arr = new char;
FindSequence(arr, 0, 2, 0, 0);
}
private static void FindSequence(char[] arr, int index, int N, int openBracket, int closeBracket){
if (closeBracket == N){
StringBuilder s = new StringBuilder();
for (int i = 0; i < arr.Length; i++){
s.Append(arr[i]);
}
Console.WriteLine(s);
s = null;
return;
}
else{
if (openBracket > closeBracket){
arr[index] = '}';
FindSequence(arr, index + 1, N, openBracket, closeBracket + 1);
}
if (openBracket < N){
arr[index] = '{';
FindSequence(arr, index + 1, N, openBracket + 1, closeBracket);
}
}
}
}
class Program{
static void Main(string[] args){
BackTracking b = new BackTracking();
b.Brackets();
}
}
}

## Output

{}{}
{{}}