<p>You are given a string <code>s</code>. You can convert <code>s</code> to a <span data-keyword="palindrome-string">palindrome</span> by adding characters in front of it.</p>

<p>Return <em>the shortest palindrome you can find by performing this transformation</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> s = "aacecaaa"
<strong>Output:</strong> "aaacecaaa"
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> s = "abcd"
<strong>Output:</strong> "dcbabcd"
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>0 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
	<li><code>s</code> consists of lowercase English letters only.</li>
</ul>

class Solution {
public:
    string shortestPalindrome(string s) {
        string rev_s = s;
        reverse(rev_s.begin(), rev_s.end());
        string l = s + "#" + rev_s;
        int m = l.size();
        std::vector<int> h(m + 1, 0); // Create a vector of size m+1 initialized to 0
        int i = 1;
        int j = 0;
        
        h[0] = -1; // Initialize h[0] to -1
        
        while (i < m) {
            h[i] = j; // Set h[i] to j
            while (j >= 0 && l[j] != l[i]) {
                j = h[j]; // Move j to the prefix function value
            }
            i++;
            j++;
        }
        
        h[m] = j; // Set the last value in h to j
        return rev_s.substr(0, s.size() - h[l.size()]) + s;
    }
};
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