<p>Given <code>n</code> pairs of parentheses, write a function to <em>generate all combinations of well-formed parentheses</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> n = 3
<strong>Output:</strong> ["((()))","(()())","(())()","()(())","()()()"]
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> n = 1
<strong>Output:</strong> ["()"]
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 8</code></li>
</ul>

class Solution {
public:
    vector<string> generateParenthesis(int n) {
        vector<string> res;
        stack<vector<int>> data;
        stack<string> strings;

        data.push({0, 0});
        strings.push("");
        while (data.size()) {
            int open = data.top()[0], close = data.top()[1];
            string cur = strings.top();

            data.pop();
            strings.pop();

            if (open == n && close == n) {
                res.push_back(cur);
            } else {
                if (open > close) {
                    data.push({open, close + 1});
                    strings.push(cur + ')');
                }
                if (open < n) {
                    data.push({open + 1, close});
                    strings.push(cur + '(');
                }
            }
        }
        return res;
    }
};
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