// Quick and dirty implementation of HashSet. 

public class HashSet<E> {
    private HashNode[] data;
    private int size;

    public HashSet(int capacity) {
        data = new HashNode[capacity];
    }

    public void add(E value) {
        if (!contains(value)) {
            int i = indexOf(value);
            data[i] = new HashNode(value, data[i]);
            size++;
        }
    }

    public boolean contains(E value) {
        int i = indexOf(value);
        HashNode current = data[i];
        while (current != null) {
            if (current.data.equals(value)) {
                return true;
            }
            current = current.next;
        }
        return false;
    }

    public void remove(E value) {
        if (contains(value)) {
            int i = indexOf(value);
            if (data[i].data.equals(value)) {
                data[i] = data[i].next;
            } else {
                HashNode current = data[i];
                while (!current.next.data.equals(value)) {
                    current = current.next;
                }
                current.next = current.next.next;
            }
            size--;
        }
    }

    public int size() {
        return size;
    }

    private int indexOf(E value) {
        return Math.abs(value.hashCode() % data.length);
    }

    private static class HashNode {
        public Object data;
        public HashNode next;

        public HashNode(Object data, HashNode next) {
            this.data = data;
            this.next = next;
        }
    }
}