package com.company;

import org.junit.Test;

import java.util.ArrayList;

import java.util.List;

public class GenerateParenthesis {

public List<String> generateParenthesis(int n) {

List<String> ans = new ArrayList();

backtrack(ans, "", 0, 0, n);

return ans;

}

public void backtrack(List<String> ans, String cur,

int open, int close, int max) {

if (cur.length() == max * 2) {

ans.add(cur);

return;

}

if (open < max)

backtrack(ans, cur + "(", open + 1, close, max);

if (close < open)

backtrack(ans, cur + ")", open, close + 1, max);

}

@Test

public void test() {

List<String> generateParenthesis = generateParenthesis(3);

for (String str : generateParenthesis) {

System.out.println(str);

}

}

}