/
Manacher.hpp
36 lines (34 loc) · 1 KB
/
Manacher.hpp
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template <class T> vector<int> manacher(const vector<T>& s) {
vector<int> R(s.size());
int i = 0, j = 0;
while (i < s.size()) {
while (i - j >= 0 && i + j < s.size() && s[i - j] == s[i + j]) ++j;
R[i] = j;
int k = 1;
while (i - k >= 0 && i + k < s.size() && k + R[i - k] < j) R[i + k] = R[i - k], ++k;
i += k;
j -= k;
}
return R;
}
struct Manacher {
vector<int> a;
template <class T> Manacher(const vector<T>& s, T DUMMY = -1) {
int m = s.size() * 2 - 1;
vector<T> t(m, DUMMY);
for (int i = 0; i < s.size(); i++) {
t[i * 2] = s[i];
}
a = manacher(t);
}
Manacher(const string& s, char DUMMY = '$') {
int m = s.size() * 2 - 1;
vector<char> t(m, DUMMY);
for (int i = 0; i < s.size(); i++) {
t[i * 2] = s[i];
}
a = manacher(t);
}
// [l, r)が回文かどうか
bool is_palindrome(int l, int r) { return a[l + r - 1] >= r - l; }
};