HashSet

#include <iostream>
#include <forward_list>
#include <string>
#include <vector>

using namespace std;

int MyHash(const string& key) {
  int result = 0;
  for (int i = 0; i < min(key.size(), 5ul); ++i)
    result = result * 37 + key[i];
  return result;
}

class HashSet {
 public:
  HashSet() : table(80) {}

  bool Has(const string& key) const;
  // Возвращает false, если дубль.
  bool Add(const string& key);
  // Возвращает false, если ключа нет.
  bool Remove(const string& key);
 private:
  vector<forward_list<string>> table;
};

bool HashSet::Has(const string& key) const {
  int hash = MyHash(key) % table.size();
  auto& current_list = table[hash];
  auto it = find(current_list.begin(), current_list.end(), key);
  return it != current_list.end();
}
bool HashSet::Add(const string& key) {
  int hash = MyHash(key) % table.size();
  auto& current_list = table[hash];
  auto it = find(current_list.begin(), current_list.end(), key);
  if (it != current_list.end()) return false;
  current_list.insert_after(current_list.before_begin(), key);
  return true;
}
bool HashSet::Remove(const string& key) {
  int hash = MyHash(key) % table.size();
  auto& current_list = table[hash];
  return current_list.remove(key);
}

int main() {
  HashSet hashset;
  char command = 0;
  string value;
  while (cin >> command >> value) {
    switch (command) {
      case '?':
        cout << (hashset.Has(value) ? "OK" : "FAIL") << endl;
        break;
      case '+':
        cout << (hashset.Add(value) ? "OK" : "FAIL") << endl;
        break;
      case '-':
        cout << (hashset.Remove(value) ? "OK" : "FAIL") << endl;
        break;
    }
  }

  return 0;
}