vector Z(const string& s) { int n = sz(s); vector z(n); for (int i = 1, x = 0; i < n; i++) { z[i] = max(0, min(z[i - x], x + z[x] - i)); while (i + z[i] < n && s[z[i]] == s[i + z[i]]) { x = i, z[i]++; }} return z; }