<p>Given a string <code>s</code>, partition <code>s</code> such that every <span data-keyword="substring-nonempty">substring</span> of the partition is a <span data-keyword="palindrome-string"><strong>palindrome</strong></span>. Return <em>all possible palindrome partitioning of </em><code>s</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> s = "aab"
<strong>Output:</strong> [["a","a","b"],["aa","b"]]
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> s = "a"
<strong>Output:</strong> [["a"]]
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 16</code></li>
	<li><code>s</code> contains only lowercase English letters.</li>
</ul>

class Solution
{
public:
    vector<vector<string>> partition(const string &s)
    {
        vector<vector<string>> result;
        vector<string> partitioning;
        solve(0, 1, s, partitioning, result);
        return result;
    }

private:
    void solve(const int from, const int to, const string &s, vector<string> &partitioning, vector<vector<string>> &result)
    {
        if (accumulate(partitioning.begin(), partitioning.end(), 0, [](const int sum, const string &ss) { return sum + ss.size(); }) == s.size())
        {
            result.push_back(partitioning);
        }

        const auto n = static_cast<int>(s.size());
        if (to == n + 1)
        {
            return;
        }

        const string ss = s.substr(from, to - from);
        if (isPalindrome(ss))
        {
            partitioning.push_back(ss);
            solve(to, to + 1, s, partitioning, result);
            partitioning.pop_back();
        }

        solve(from, to + 1, s, partitioning, result);
    }

    bool isPalindrome(const string &s)
    {
        if (!s.empty())
        {
            auto l = s.begin();
            auto r = prev(s.end());

            while (l <= r)
            {
                if (*l != *r)
                {
                    return false;
                }

                ++l;
                --r;
            }
        }

        return true;
    }
};
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