Suffix automata (SAM) board from Jly

struct SuffixAutomaton {
    static constexpr int ALPHABET_SIZE = 26, N = 1e5;
    struct Node {
        int len;
        int link;
        int next[ALPHABET_SIZE];
        Node() : len(0), link(0), next{} {}
    } t[2 * N];
    int cntNodes;
    SuffixAutomaton() {
        cntNodes = 1;
        std::fill(t[0].next, t[0].next + ALPHABET_SIZE, 1);
        t[0].len = -1;
    }
    int extend(int p, int c) {
        if (t[p].next[c]) {
            int q = t[p].next[c];
            if (t[q].len == t[p].len + 1)
                return q;
            int r = ++cntNodes;
            t[r].len = t[p].len + 1;
            t[r].link = t[q].link;
            std::copy(t[q].next, t[q].next + ALPHABET_SIZE, t[r].next);
            t[q].link = r;
            while (t[p].next[c] == q) {
                t[p].next[c] = r;
                p = t[p].link;
            }
            return r;
        }
        int cur = ++cntNodes;
        t[cur].len = t[p].len + 1;
        while (!t[p].next[c]) {
            t[p].next[c] = cur;
            p = t[p].link;
        }
        t[cur].link = extend(p, c);
        return cur;
    }
};