74 lines
1.8 KiB
C++
74 lines
1.8 KiB
C++
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template <size_t N>
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struct SAM {
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vector<int> fa, len;
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vector<bool> cloned;
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vector<int> cnt;
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vector<array<int, N>> ch;
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int last;
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int tot;
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int create(int _fa, int _len, bool _cloned, array<int, N>&& _ch) {
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fa.emplace_back(_fa);
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len.emplace_back(_len);
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cloned.emplace_back(_cloned);
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ch.emplace_back(_ch);
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return tot++;
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}
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SAM(void) : fa(2), len(2), cloned(2), ch(2), last(1), tot(2) {}
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void push_back(size_t c) {
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int p = last;
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int nw = create(0, len[p] + 1, false, {});
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while (p != 0 and ch[p][c] == 0) {
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ch[p][c] = nw;
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p = fa[p];
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}
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if (p == 0) {
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fa[nw] = 1;
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} else {
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int q = ch[p][c];
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if (len[q] == len[p] + 1) {
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fa[nw] = q;
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} else {
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int nq = create(fa[q], len[p] + 1, true, array(ch[q]));
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fa[nw] = fa[q] = nq;
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while (p != 0 and ch[p][c] == q) {
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ch[p][c] = nq;
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p = fa[p];
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}
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}
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}
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last = nw;
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}
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template <typename T>
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optional<int> find(const basic_string<T>& seq) {
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int p = 1;
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for (auto&& c : seq) {
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if (ch[p][c] == 0) {
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return nullopt;
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}
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p = ch[p][c];
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}
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return p;
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}
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// Fill `cnt` with the number of occurrences of each substring.
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void populate(void) {
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cnt.assign(tot, 0);
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vector<int> idx(tot);
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iota(idx.begin(), idx.end(), 0);
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sort_by_key(idx.begin(), idx.end(), expr(len[i], auto&& i), greater());
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for (auto&& v : idx) {
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if (v > 1 and not cloned[v]) {
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cnt[v] += 1;
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}
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cnt[fa[v]] += cnt[v];
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}
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}
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};
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