maxheap.java

来自「一个java程序编写的svm支持向量机小程序」· Java 代码 · 共 75 行

package edu.udo.cs.mySVMdb.Util;

public class MaxHeap extends Heap
{
    /**
     * Implements a MaxHeap on n doubles and ints
     * @author Stefan R黳ing
     * @version 1.0
     */


    public MaxHeap(int n){
	init(n);
    };


    public final void add(double value, int index)
    {
	if(last < the_size){
	    heap[last] = value;
	    indizes[last] = index;
	    last++;
	    if(last == the_size){
		for(int j=last;j>0;j--){
		    heapify(j-1,last+1-j);
		};
	    };
	}
	else if(value >= heap[0]){
	    heap[0] = value;
	    indizes[0] = index;
	    heapify(0,last);
	};
    };


    protected final void heapify(int start, int size)
    {
	double[] my_heap = heap;
	boolean running = true;
	int pos = 1;
	int left, right, largest;
	double dummyf;
	int dummyi;
	start--;  // other variables counted from 1
	while(running){
	    left = 2*pos;
	    right = left+1;
	    if((left<=size) && 
	       (my_heap[left+start] < my_heap[start+pos])){
		largest = left;
	    }
	    else{
		largest = pos;
	    };
	    if((right<=size) && 
	       (my_heap[start+right] < my_heap[start+largest])){
		largest = right;
	    };
	    if(largest == pos){
		running = false;
	    }
	    else{
		dummyf = my_heap[start+pos];
		dummyi = indizes[start+pos];
		my_heap[start+pos] = my_heap[start+largest];
		indizes[start+pos] = indizes[start+largest];
		my_heap[start+largest] = dummyf;
		indizes[start+largest] = dummyi;
		pos = largest;
	    };
	};
    };
};