StringBuilder parenthesis

import java.util.ArrayList;

public class GeneratePaqrenthesis {
    static void solve(ArrayList<StringBuilder> output, int open, int close, StringBuilder ans){
        if(open == 0 && close == 0){
            output.add(new StringBuilder(ans));
            return;
        }

        if(open>0){
            ans.append("(");
            solve(output,open - 1, close, ans);
            ans.delete(ans.length()-1,ans.length());
        }

        if(close>open){
            ans.append(")");
            solve(output,open, close-1, ans);
            ans.delete(ans.length()-1,ans.length());
        }
    }
    public static void main(String[] args) {

        int open = 2;
        int close = 2;
        StringBuilder ans= new StringBuilder();
        ArrayList<StringBuilder> output = new ArrayList<>();

        solve(output,open,close,ans);
   for(StringBuilder s: output){
       System.out.println(s);
   }

    }
}

//here the output is correct
//(())
//()()