class SolutionHashTable {
  public Entry[] table;
  public int capacity;

  /**
   * Constructs a new HashTable.
   *
   * Capacity of the hash table can not be 0 or negative.
   *
   * @param capacity
   *     to be used as capacity of the table.
   * @throws IllegalArgumentException
   *     if the input capacity is invalid.
   */
  public SolutionHashTable(int capacity) {
    if(capacity <= 0)throw new IllegalArgumentException();
    table = new Entry[capacity];
    this.capacity = capacity;
  }

  /**
   * Add a new Entry to the hash table,
   * uses linear probing to deal with collisions.
   *
   * Returns false, if the key is null or the table is full.
   *
   * @param key
   *     String representing the key of the entry.
   * @param value
   *     String representing the value of the entry.
   * @return true iff entry has been added successfully, else false.
   */
  public boolean put(String key, String value) {

    if(key == null)return false;
    int hash = hash(key);
    Entry e = new Entry(key,value);
    for(int i = 0; i < capacity; i++){
      Entry en = table[hash];
      if(en == null || (en.getKey() == null && en.getValue() == null) || en.getKey() == e.getKey()){
        table[hash] = e;
        return true;
      }
      hash = (hash+1) % capacity;
    }
    return false;
  }

  /**
   * Retrieve the value of the entry associated with this key.
   *
   * Returns null, if the key is null.
   *
   * @param key
   *     String representing the key of the entry to look for.
   * @return value of the entry as String iff the entry with this key is found in the hash table, else null.
   */
  public String get(String key) {
    if(key == null)return null;
    int hash = hash(key);

    for(int i = 0; i < capacity; i++){
      if(table[hash] == null)return null;

      if(table[hash].getKey() == key){
        return table[hash].getValue();
      }
      hash = (hash+1) % capacity;
    }
    return null;
  }

  /**
   * Remove the entry associated with this key from the hash table.
   *
   * Returns false, if the key is null.
   *
   * @param key
   *     String representing the key of the entry to remove.
   * @return true iff the entry has been successfully removed, else false.
   */
  public boolean remove(String key) {

    if(key == null)return false;
    int hash = hash(key);

    for(int i = 0; i < capacity; i++){
      if(table[hash] == null)return false;
      if(table[hash].getKey() == key){
        setDefunct(hash);
        return true;
      }
      hash = (hash+1) % capacity;
    }
    return false;
  }

  /**
   * Takes as input an index and sets the entry in that location as defunct.
   *
   * @param index
   *     The index of the spot that is defunct.
   */
  public void setDefunct(int index) {
    this.table[index] = new Entry(null, null);
  }

  /**
   * Hashes a string representing a key.
   *
   * @param key
   *     String that needs to be hashed.
   * @return the hashcode of the string, modulo the capacity of the HashTable.
   */
  public int hash(String key) {
    return Math.abs(key.hashCode()) % capacity;
  }
}
//