constexpr int MAX_CHAR = 256; struct SuffixArray { int n; vector SA, LCP; vector> P; SuffixArray(const string& s) : n(sz(s)), SA(n), LCP(n), P(__lg(2 * n - 1) + 1, vector(n)) { P[0].assign(all(s)); iota(all(SA), 0); sort(all(SA), [&](int a, int b) {return s[a] < s[b];}); vector x(n); for (int k = 1, c = 1; c < n; k++, c *= 2) { iota(all(x), n - c); for (int ptr = c; int i : SA) if (i >= c) x[ptr++] = i - c; vector cnt(k == 1 ? MAX_CHAR : n); for (int i : P[k-1]) cnt[i]++; partial_sum(all(cnt), begin(cnt)); for (int i : x | views::reverse) SA[--cnt[P[k-1][i]]] = i; auto p = [&](int i) {return i < n ? P[k-1][i] : -1;}; for (int i = 1; i < n; i++) { int a = SA[i-1], b = SA[i]; P[k][b] = P[k][a] + (p(a) != p(b) || p(a+c) != p(b+c)); }} for (int i = 1; i < n; i++) LCP[i] = lcp(SA[i-1], SA[i]); } int lcp(int x, int y) {//x & y are text-indices, not SA-indices if (x == y) return n - x; int res = 0; for (int i = sz(P) - 1; i >= 0 && max(x, y) + res < n; i--) { if (P[i][x + res] == P[i][y + res]) res |= 1 << i; } return res; } };