<p>Given a positive integer <code>n</code>, find <em>the smallest integer which has exactly the same digits existing in the integer</em> <code>n</code> <em>and is greater in value than</em> <code>n</code>. If no such positive integer exists, return <code>-1</code>.</p>

<p><strong>Note</strong> that the returned integer should fit in <strong>32-bit integer</strong>, if there is a valid answer but it does not fit in <strong>32-bit integer</strong>, return <code>-1</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> n = 12
<strong>Output:</strong> 21
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> n = 21
<strong>Output:</strong> -1
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
</ul>

class Solution {
public:
    int nextGreaterElement(int n) {
    std::string num = std::to_string(n);

    // Use next_permutation to find the next lexicographical permutation
    if (std::next_permutation(num.begin(), num.end())) {
        long nextNum = std::stol(num); // Convert string back to long to handle overflow

        // Check if the next number fits in 32-bit signed integer
        if (nextNum <= INT_MAX) {
            return static_cast<int>(nextNum); // Return as int if it's within bounds
        }
    }

    // If no valid permutation or it exceeds 32-bit integer range
    return -1;
}
};
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