JavaAlgorithms/DataStructures/Heaps/Heap.java

package DataStructures.Heaps;

/**
 * Interface common to heap data structures.<br>
 * <p>Heaps are tree-like data structures that allow storing elements in a specific
 * way. Each node corresponds to an element and has one parent node (except for the root) and
 * at most two children nodes. Every element contains a key, and those keys
 * indicate how the tree shall be built. For instance, for a min-heap, the key of a node shall
 * be greater than or equal to its parent's and lower than or equal to its children's (the opposite rule applies to a
 * max-heap).</p>
 * <p>All heap-related operations (inserting or deleting an element, extracting the min or max) are performed in
 * O(log n) time.</p>
 *
 * @author Nicolas Renard
 */
public interface Heap {

    /**
     * @return the top element in the heap, the one with lowest key for min-heap or with
     * the highest key for max-heap
     * @throws EmptyHeapException if heap is empty
     */
    HeapElement getElement() throws EmptyHeapException;

    /**
     * Inserts an element in the heap. Adds it to then end and toggle it until it finds its
     * right position.
     *
     * @param element an instance of the HeapElement class.
     */
    void insertElement(HeapElement element);

    /**
     * Delete an element in the heap.
     *
     * @param elementIndex int containing the position in the heap of the element to be deleted.
     */
    void deleteElement(int elementIndex);

}