// Very bare bones implementation of HashSet to introduce the idea of hashing.
// Does not handle collisions.
public class HashStringSet {
   private String[] hashTable;
   private int size;
   
   public static final int DEFAULT_CAPACITY = 10;
   
   // Constructs a new, empty set
   public HashStringSet() {
      hashTable = new String[DEFAULT_CAPACITY];
      size = 0;
   }
   
   // Adds the specified element to this set if it is not already present.
   public void add(String value) {
      if (!contains(value)) {
         int index = hashIndex(value);
         hashTable[index] = value;
         size++;
      }
   }
   
   // Returns true if this set contains the specified value and false otherwise
   public boolean contains(String value) {
       int index = hashIndex(value);
       return value.equals(hashTable[index]);
   }
   
   // Returns the index that this element belongs at
   private int hashIndex(String value) {
      int index = Math.abs(value.hashCode() % hashTable.length);
      return index;
   }
   
   // Returns the number of elements in this set
   public int size() {
      return this.size;
   }
}