河源电厂2025年度铁路专用线线路整治运检项目招标公告（原标题：河源电厂2025年度铁路专用线线路整治运检项目）

```cpp
#include 
#include 
#include 
#include 
using namespace std;
class Solution {
public:
    vector generateParenthesis(int n) {
        vector result;
        string current;
        backtrack(result, current, 0, 0, n);
        return result;
    }
private:
    void backtrack(vector& result, string& current, int open, int close, int max) {
        if (current.length() == max * 2) {
            result.push_back(current);
            return;
        }
        if (open < max) {
            current += "(";
            backtrack(result, current, open + 1, close, max);
            current.pop_back();
        }
        if (close < open) {
            current += ")";
            backtrack(result, current, open, close + 1, max);
            current.pop_back();
        }
    }
};
int main() {
    Solution solution;
    int n;
    cout << "请输入括号对数: ";
    cin >> n;
    vector result = solution.generateParenthesis(n);
    for (const string& s : result) {
        cout << s << endl;
    }
    return 0;
}