Generating valid paranthesis (e.g. (()()), ()()(), ....) is a challenge from Cracking Code Interview Book

GenerateValidParanthesisPermutations.java

import java.util.LinkedList;
import java.util.List;

public class GenerateValidParanthesisPermutations {
	
	private static final String OPEN = "(";
	private static final String CLOSE = ")";

	public static void main(String[] args) {
		List<String> permutations = generateValidPermuations(3);
		for (String permutation : permutations) {
			System.out.println(permutation);
		}
	}

	private static List<String> generateValidPermuations(int n) {
		StringBuilder currentBuilder = new StringBuilder(OPEN);
		return doGenerate(n*2, currentBuilder, 1, 0);
	}
	
	private static List<String> doGenerate(int n, StringBuilder currentBuilder, int openCount, int closeCount) {
		List<String> permutations = new LinkedList<>();
		if (closeCount == n / 2 && openCount == n / 2) {
			permutations.add(currentBuilder.toString());
			return permutations;
		}
		
		if (openCount < n / 2 && openCount >= closeCount) {
			StringBuilder newBuilder = new StringBuilder();
			newBuilder.append(currentBuilder.toString());
			newBuilder.append(OPEN);
			permutations.addAll(doGenerate(n, newBuilder, openCount + 1, closeCount));
		}
		
		if (closeCount < n / 2)  {
			StringBuilder newBuilder = new StringBuilder();
			newBuilder.append(currentBuilder.toString());
			newBuilder.append(CLOSE);
			permutations.addAll(doGenerate(n, newBuilder, openCount, closeCount + 1));				
		}
		return permutations;
	}