29 lines
725 B
C++
29 lines
725 B
C++
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template <typename T>
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vector<int> manacher(const vector<T>& s, const T& never) {
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vector<T> t = { never };
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for (auto&& c : s) {
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t.emplace_back(c);
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t.emplace_back(never);
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}
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int n = t.size();
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vector<int> r(n);
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for (int i = 0, j = 0; i < n; ++i) {
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if (2 * j - i >= 0 && j + r[j] > i) {
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r[i] = min(r[2 * j - i], j + r[j] - i);
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}
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while (i - r[i] >= 0 && i + r[i] < n && t[i - r[i]] == t[i + r[i]]) {
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r[i] += 1;
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}
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if (i + r[i] > j + r[j]) {
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j = i;
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}
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}
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for (int i = 0; i < n; i += 2) {
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r[i] = (r[i] - 1) / 2;
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}
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for (int i = 1; i < n; i += 2) {
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r[i] /= 2;
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}
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return r;
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}
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