牛客60（括号生成）

60.括号生成

 

 

 

import java.util.*;


public class Solution {
    ArrayList<String> res = new ArrayList<>();
    public ArrayList<String> generateParenthesis (int n) {
        traversal(0, 0, n, "");
        return res;
    }
    public void traversal(int left, int right, int n, String temp) {
        if (left == n && right == n) {
            res.add(temp);
            return;
        }
        if (left < n) {
            traversal(left + 1, right, n, temp + "(");
        }
        
        if (right < n && right < left) {
            traversal(left, right+1, n, temp + ")");
        }
    }
}