括号生成

#include <iostream>
#include <string>
#include <vector>

using namespace std;

class Solution {
public:
    void backtrack(vector<string>& ans, string& cur, int open, int close, int n) {
        if (cur.size() == n * 2) {
            ans.push_back(cur);
            return;
        }
        if (open < n) {
            cur.push_back('(');
            backtrack(ans, cur, open + 1, close, n);
            cur.pop_back();
        }
        if (close < open) {
            cur.push_back(')');
            backtrack(ans, cur, open, close + 1, n);
            cur.pop_back();
        }
    }
    vector<string> generateParenthesis(int n) {
        vector<string> result;
        string current;
        backtrack(result, current, 0, 0, n);
        return result;
    }
};

int main() {
    Solution solution;
    vector<string> result = solution.generateParenthesis(3);
    vector<string>::iterator it;
    for (it = result.begin(); it != result.end(); it++) {
        cout << *it <<endl;
    }
}