給出 n 代表生成括號的對數(shù)港粱，請你寫出一個函數(shù)，使其能夠生成所有可能的并且有效的括號組合淤毛。
例如
給出 n = 3环葵，生成結(jié)果為：
[
"((()))",
"(()())",
"(())()",
"()(())",
"()()()"
]
代碼
class Solution {
public:
vector<string> generateParenthesis(int n) {
vector<string> res;
generateParenthesisDFS(n, n, "", res);
return res;
}
void generateParenthesisDFS(int left, int right, string out, vector<string> &res) {
if (left > right) return;
if (left == 0 && right == 0) res.push_back(out);
else {
if (left > 0) generateParenthesisDFS(left - 1, right, out + '(', res);
if (right > 0) generateParenthesisDFS(left, right - 1, out + ')', res);
}
}
};
