堆排序（java 语言实现）

来源：互联网发布：淘宝上架时间技巧编辑：程序博客网时间：2024/05/17 16:56
可以用数组或者线性表实现 Heap ，关键是理清楚
当前节点的坐标和父节点的坐标以及左右孩子的坐标的关系，比如当前坐标是 i 其他节点的坐标如何表示。然后就是添加删除的原则。
package com.shan.heapSort;public class Heap<E extends Comparable<E>> {    private java.util.ArrayList<E> list = new java.util.ArrayList<E>();    /** Create a default heap */    public Heap() {    }    /** Create a heap from an array of objects */    public Heap(E[] objects) {        for (int i = 0; i < objects.length; i++) {            add(objects[i]);        }    }    /** Add a new object into the heap */    public void add(E e) {        list.add(e); // Append to the heap        int currentIndex = list.size() - 1;        while (currentIndex > 0) {            int parentIndex = (currentIndex - 1) / 2;            E current = list.get(currentIndex);            E parent = list.get(parentIndex);            if (current.compareTo(parent) > 0) {                list.set(parentIndex, current);                list.set(currentIndex, parent);                currentIndex = parentIndex;            } else {                break; // the tree is a heap now            }        }        System.out.println(list);    }    /** Remove root from the heap */    public E remove() {        // if the Heap is empty return null        if (list.size() == 0)            return null;        // cached root(the first element of the list),        // and then replace it with the last element in the list        E removedOject = list.get(0);        list.set(0, list.get(list.size() - 1));        list.remove(list.size() - 1);        // find the proper place for the current element        int currentIndex = 0;        while (currentIndex < list.size()) {            int leftChildIndex = 2 * currentIndex + 1;            int rightChildIndex = 2 * currentIndex + 2;            // Find the max between the tow child            if (leftChildIndex >= list.size()) // the tree is a heap                break;            int maxIndex = leftChildIndex;            if (rightChildIndex < list.size()) {                if (list.get(maxIndex).compareTo(list.get(rightChildIndex)) < 0) {                    maxIndex = rightChildIndex;                }            }            // Swap if the current node is less then the maximum            E current = list.get(currentIndex);            E maxChild = list.get(maxIndex);            if (current.compareTo(maxChild) < 0) {                list.set(maxIndex, current);                list.set(currentIndex, maxChild);                currentIndex = maxIndex;            } else {                break;            }        }        return removedOject;    }    /** Remove the root from the heap */    public E remove2() {        if (list.size() == 0)            return null;        E removedObject = list.get(0);        list.set(0, list.get(list.size() - 1));        list.remove(list.size() - 1);        int currentIndex = 0;        while (currentIndex < list.size()) {            int leftChildIndex = 2 * currentIndex + 1;            int rightChildIndex = 2 * currentIndex + 2;            // Find the maximum between two children            if (leftChildIndex >= list.size())                break; // The tree is a heap            int maxIndex = leftChildIndex;            if (rightChildIndex < list.size()) {                if (list.get(maxIndex).compareTo(list.get(rightChildIndex)) < 0) {                    maxIndex = rightChildIndex;                }            }            // Swap if the current node is less than the maximum            if (list.get(currentIndex).compareTo(list.get(maxIndex)) < 0) {                E temp = list.get(maxIndex);                list.set(maxIndex, list.get(currentIndex));                list.set(currentIndex, temp);                currentIndex = maxIndex;            } else                break; // The tree is a heap        }        return removedObject;    }    /*public ArrayList<E> heapSort() {        for (int i = 0; i < list.size(); i++) {            E temp  = list.get(i);            list.set(i, this.remove());        }        return list;    }*/    /** Get the number of nodes in the tree */    public int getSize() {        return list.size();    }    public static void main(String[] args) {        Integer[] list = { 2, 1, 3, 5, 0, 12, 34, 22, 89, 11 };        Heap<Integer> heap = new Heap<>(list);        for (int i = list.length - 1; i >=0; i--) {            //System.out.print(heap.remove() + " ");            list[i] = heap.remove();        }        for (int i = 0; i < list.length; i++) {            System.out.print(list[i] + " ");        }    }}
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