最小堆和最大堆的JAVA实现

标签：数据结构

/**
 * 文件名：BinaryHeap.java
 * 时间：2014年11月3日下午7:15:34
 * 作者：修维康
 */
package chapter6;

import java.util.*;

/**
 * 类名：BinaryHeap 说明：建立一个最小堆
 */
class MinHeap<AnyType extends Comparable<? super AnyType>> {
	private int currentSize;
	private static final int DEFAULT_CAPACITY = 10;
	private AnyType[] array;

	public MinHeap(AnyType[] items) {
		currentSize = items.length;
		array = (AnyType[]) new Comparable[currentSize + 1];
		int i = 1;
		for (AnyType item : items)
			array[i++] = item;
		buildHeap();
	}

	/**
	 * 方法名：percolateDown
	 * 说明：
	 */
	private void percolateDown(int position) {
		AnyType temp = array[position];
		int child;
		for (; position * 2 <= currentSize; position = child) {
			child = 2 * position;
			if (child != currentSize
					&& array[child + 1].compareTo(array[child]) < 0)
				child++;
			if (array[child].compareTo(temp) < 0)
				array[position] = array[child];

			else
				break;
		}
		array[position] = temp;
	}

	/**
	 * 方法名：buildHeap
	 * 说明：下滤的顺序很关键 从中间开始不断向上依次下滤
	 */
	private void buildHeap() {
		for (int i = currentSize / 2; i > 0; i--)
			percolateDown(i);
	}

	public void insert(AnyType x) {
		if (currentSize >= array.length - 1)
			enlargeArray(array.length * 2 + 1);
		int hole = ++currentSize;
		while (hole > 1 && x.compareTo(array[hole / 2]) < 0) {
			array[hole] = array[hole / 2];
			hole /= 2;
		}
		array[hole] = x;
	}

	private void enlargeArray(int capacity) {
		AnyType[] oldArr = array;
		AnyType[] newArr = (AnyType[]) new Comparable[capacity];
		for (int i = 1; i < array.length; i++)
			newArr[i] = oldArr[i];
		array = newArr;
	}

	public boolean isEmpty() {
		return currentSize == 0;
	}

	public AnyType deleMin() {
		if (!isEmpty()) {
			AnyType min = array[1];
			array[1] = array[currentSize--];
			percolateDown(1);
			return min;
		}
		return null;

	}

	public String toString() {
		StringBuffer sb = new StringBuffer();
		for (int i = 1; i <= currentSize; i++)
			sb.append(array[i] + " ");
		return new String(sb);
	}
}

/**
 * 类名：MaxHeap 说明：最大堆操作与建堆
 */
class MaxHeap<AnyType extends Comparable<? super AnyType>> {
	private AnyType[] array;
	private int currentSize;

	public MaxHeap(AnyType[] arr) {
		currentSize = arr.length;
		array = (AnyType[]) new Comparable[currentSize + 1];
		int i = 1;
		for (int j = 0; j < arr.length; j++)
			array[i++] = arr[j];
		buildHeap();
	}

	/**
	 * 方法名：buildHeap
	 * 说明：从中间开始到结束 不断上滤
	 */
	private void buildHeap() {
		for (int i = currentSize /2; i <= currentSize; i++)
			percolateUp(i);
	}

	private void percolateUp(int position) {
		AnyType temp = array[position];
		while (position > 1) {
			if (array[position / 2].compareTo(temp) < 0) {
				array[position] = array[position / 2];
				position /= 2;
			} else
				break;
		}
		array[position] = temp;
	}
	private boolean isEmpty(){
		return currentSize == 0;
	}
	public AnyType deleMax(){
		AnyType max = array[1];
		AnyType temp = array[currentSize--];
		int position = 1;
		int child;
		while(position *2 <= currentSize){
			child = 2 * position;
			if(child!=currentSize&&array[child].compareTo(array[child + 1]) < 0)
				child++;
			if(array[child].compareTo(temp) > 0)
				array[position] = array[child];
			else 
				break;
			position = child;
		}
		array[position] = temp;
		return max;
	}
	public void insert(AnyType x){
		if(currentSize == array.length -1)
			enlargeArray( 2* currentSize +1);
		array[++currentSize] = x;
		percolateUp(currentSize);
	}
	private void enlargeArray(int capacity) {
		AnyType[] oldArr = array;
		AnyType[] newArr = (AnyType[]) new Comparable[capacity];
		for (int i = 1; i < array.length; i++)
			newArr[i] = oldArr[i];
		array = newArr;
	}
	public String toString() {
		StringBuffer sb = new StringBuffer();
		for (int i = 1; i <= currentSize; i++)
			sb.append(array[i] + " ");
		return new String(sb);
	}

}

public class HeapTest {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Integer[] arr = new Integer[] { 9,8,7,6,5, 4, 3, 2};
		MinHeap min = new MinHeap(arr);
		min.insert(10);
		min.deleMin();
		System.out.println(min);
		Integer[] arr2 = new Integer[] { 1, 2, 3, 4, 5,6,7,8,9,10};
		MaxHeap max = new MaxHeap(arr2);
		max.deleMax();
		max.insert(10);
		System.out.println(max);

	}
}

最小堆和最大堆的JAVA实现

标签：数据结构

原文地址：http://blog.csdn.net/xiuweikang/article/details/40787145