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SPL(Structured Process Language) A programming language specially for structured data computing.

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package com.scudata.util;

/**
 * ????ȡ????n??ֵ?Ķ?
 * @author WangXiaoJun
 *
 */
public class MaxHeap {
	// С????(?Ѷ?Ԫ????С)??????Ԫ?ؽ???ʱ?ȸ??Ѷ????бȽϣ?????ȶѶ?С????
	private Object []heap; // ???ڱ?????????????ڵ??ֵ??????0??λ?ÿ???
	private int maxSize; // ??ౣ????ֵ??????
	private int currentSize; // ??ǰ???е?ֵ??????

	/**
	 * ????ȡmaxSize?????ֵ?Ķ?
	 * @param maxSize ????
	 */
	public MaxHeap(int maxSize) {
		this.heap = new Object[maxSize + 1];
		this.maxSize = maxSize;
		this.currentSize = 0;
	}

	/**
	 * ???ص?ǰ??ֵ????
	 * @return ????
	 */
	public int size() {
		return currentSize;
	}

	/**
	 * ??????ֵ
	 * @param o ֵ
	 * @return true????ǰֵ??ʱ??????maxSize??ֵ??Χ?ڣ?false????ǰֵ̫С??????
	 */
	public boolean insert(Object o) {
		Object []heap = this.heap;
		if (currentSize == maxSize) {
			if (Variant.compare(o, heap[1], true) <= 0) {
				return false;
			} else {
				deleteRoot();
				return insert(o);
			}
		} else {
			int i = ++currentSize;
			while (i != 1 && Variant.compare(o, heap[i/2], true) < 0) {
				heap[i] = heap[i/2]; // ??Ԫ??????
				i /= 2;              // ???򸸽ڵ?
			}

			heap[i] = o;
			return true;
		}
	}

	/**
	 * ɾ?????ڵ?
	 */
	private void deleteRoot() {
		// ?????һ??Ԫ?ط??ڶѶ???Ȼ???Զ????µ???
		Object []heap = this.heap;
		int currentSize = this.currentSize;
		Object o = heap[currentSize];

		int i = 1;
		int c = 2; // ?ӽڵ?
		while(c < currentSize) {
			// ?ҳ???С???ӽڵ?
			int rc = c + 1;  // ???ӽڵ?
			if (rc < currentSize && Variant.compare(heap[rc], heap[c], true) < 0) {
				c = rc;
			}

			if (Variant.compare(o, heap[c], true) > 0) {
				heap[i] = heap[c];
				i = c;
				c *= 2;
			} else {
				break;
			}
		}

		heap[i] = o;
		heap[currentSize] = null;
		this.currentSize--;
	}

	/**
	 * ????????Ԫ??
	 * @return Ԫ??????
	 */
	public Object[] toArray() {
		Object []objs = new Object[currentSize];
		System.arraycopy(heap, 1, objs, 0, currentSize);
		//Arrays.sort(objs);
		return objs;
	}
}