Algoritmo KMP
#define ll long long int
#define vll vector<long long int>
ll kmp(string s)
{
ll n = s.size();
vll lps(n, 0); // longest prefix suffix
for (ll i = 1; i < n; i++)
{
ll j = lps[i - 1];
while (j > 0 && s[i] != s[j])
{
j = lps[j - 1];
}
if (s[i] == s[j])
{
j++;
}
lps[i] = j;
}
return lps[n - 1];
}
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