#include using namespace std; // change input here //string str = "Sunny day! #Ita #vvv"; //string h = "#Ita"; //string str = "#Ita #picture_contest"; //string h = "#Ita"; //string str = "#Ita #picture_contest #Ita"; //string h = "#Ita"; string str = "Hello #World"; string h = ""; template vector kmp_table(const T &s) { int n = s.size(), k = 0; vector p(n, 0); for (int i = 1; i < n; i++) { while (k > 0 && !(s[i] == s[k])) { k = p[k - 1]; } if (s[i] == s[k]) { k++; } p[i] = k; } return p; } template vector kmp_search(const T &s, const T &w, const vector &p) { if (s.empty()) return vector(); int n = s.size(), m = w.size(); assert((int) p.size() == n); vector res; int k = 0; for (int i = 0; i < m; i++) { while (k > 0 && (k == n || !(w[i] == s[k]))) { k = p[k - 1]; } if (w[i] == s[k]) { k++; } if (k == n) { res.push_back(i - n + 1); } } return res; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n = h.size(), m = str.size(); vector oc = kmp_search(h, str, kmp_table(h)); if (oc.empty()) { cout << str << "\n"; } else { int idx = -1; for (int z : oc) { int i = z, len = 0; while (i < m) { char c = str[i]; if (c == ' ') { break; } len++; i++; } if (len == n) { idx = z; break; } } if (idx == -1) { cout << str << "\n"; } else { cout << str.substr(0, idx) + str.substr(idx + n) << "\n"; } } return 0; }

[Challenge] Hashtag