package keepthinker.sort;import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.ListIterator;
import java.util.PriorityQueue;
import java.util.Random;public class MyPriorityQueue<T> {private static final int SIZE=10;Comparator<T> cp;ArrayList<T> list=new ArrayList<T>();public MyPriorityQueue(Comparator<T> cp){this.cp=cp;}/**取最大优先元素：获取根元素，并且使其与最堆底元素相交换，删除堆底元素，进行一次最大堆运算。*/public T extractMax(){if(list.size()==0) return null;T max= list.get(0);Collections.swap(list, 0, list.size()-1);list.remove(list.size()-1);Object[] ls=list.toArray();HeapList<T> hList=new HeapList(ls);maxHeapify(hList, 0);ListIterator<T> i = list.listIterator();for (int j=0; j<ls.length; j++) {i.next();i.set((T)ls[j]);}return max;}/**插入新元素：插入元素于最堆底，然后递归与父节点比较大小，满足条件就交换*/public void insert(T elem){list.add(elem);increaseKey(list.size()-1, elem);}/** 修改队列中元素：若修改的优先级小于原来则返回false，若大于则与父节点递归交换*/public boolean increaseKey(int i,T elem){if(cp.compare(elem, list.get(i))<0) return false;list.set(i, elem);int j;while(i!=0){j=((i-1)>>1);//>>1 意思为除以2（性能优化），获取父节点位置if(cp.compare(list.get(i),list.get(j))>0)Collections.swap(list, i, j);i=j;}return true;}private  void maxHeapify(HeapList<T> a,int i){int l=2*i+1;//left leafint r=2*i+2;//right leafint largest;if(l<a.heapSize&&cp.compare(a.arr[l],a.arr[i])>0){largest=l;}else{largest=i;}if(r<a.heapSize&&cp.compare(a.arr[r],a.arr[largest])>0){largest=r;}if(largest!=i){T temp=a.arr[i];a.arr[i]=a.arr[largest];a.arr[largest]=temp;maxHeapify(a,largest);}}private  static class HeapList<T>{public T[] arr;public int heapSize;public HeapList(T[] arr){this.arr= arr;this.heapSize=arr.length;}}public static void main(String[] args){MyPriorityQueue<Integer> que=new MyPriorityQueue<Integer>(new IntegerCondition());Random ra=new Random();for(int i=0;i<SIZE;i++)que.insert(ra.nextInt(1000));for(int i=0;i<SIZE;i++){System.out.println(que.extractMax());}}
}
/*** the absolute value of elem must not bigger than Integer.MAX_VALUE/2.* 11 12 5 28 92 9 8* @author KESHENGKAI** @param <Integer>*/
class IntegerCondition<Integer> implements Comparator<Integer>{@Overridepublic int compare(Integer arg0, Integer arg1) {// TODO Auto-generated method stubint a1=(java.lang.Integer) arg0;int a2=(java.lang.Integer) arg1;return  a1-a2;}}
class StringCondition<String> implements Comparator<String>{@Overridepublic int compare(String o1, String o2) {// TODO Auto-generated method stubreturn ((java.lang.String)o1).compareTo((java.lang.String)o2);}}