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// q = 29, 53, 101, 257, 1009, 65537
// or choose q random from [sigma, m)
// m = 1500000001, 1600000009, 1700000009
struct Hasher {
vector<ll> power = {1}, pref = {0};
ll m, q; char c;
Hasher(const string& s, ll m, ll q, char c) :
m(m), q(q), c(c) {
for (char x : s) {
power.push_back(power.back() * q % m);
pref.push_back((pref.back() * q % m + (x - c)) % m);
}}
ll hash(int l, int r) { // Berechnet hash(s[l..r)).
return (pref[r] - power[r-l] * pref[l] % m + m) % m;
}
};
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