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package structures;
import java.util.ArrayList;
public final class Heap<T extends Comparable<? super T>> {
@SuppressWarnings("unchecked")
public Heap(int maxSize, boolean rollover_){
int len=maxSize+1;
if((len&1)==1){len++;} //Array size is always even.
CAPACITY=maxSize;
array=(T[])new Comparable[len];
rollover=rollover_;
// queue=new PriorityQueue<T>(maxSize);
}
public boolean add(T t){
assert(size==0 || array[size]!=null);
assert(rollover || size<CAPACITY);
if(size>=CAPACITY){
if(t.compareTo(array[1])<=0){return false;}
poll(); //Turns into a rolling buffer by removing smallest value.
// {//This is a more efficient alternative to poll() and percDown(), but the result is slightly different.
// array[1]=t;
// percUp(1);
// return true;
// }
}
assert(size<CAPACITY);
//assert(testForDuplicates());
// assert(queue.size()==size);
// queue.add(t);
assert(size==0 || array[size]!=null);
size++;
array[size]=t;
percDown(size);
// assert(queue.size()==size);
// assert(queue.peek()==peek());
//assert(testForDuplicates());
return true;
}
public T peek(){
//assert(testForDuplicates());
// assert(queue.size()==size);
if(size==0){return null;}
// assert(array[1]==queue.peek()) : size+", "+queue.size()+"\n"+
// array[1]+"\n"+
// array[2]+" , "+array[3]+"\n"+
// array[4]+" , "+array[5]+" , "+array[6]+" , "+array[7]+"\n"+
// queue.peek()+"\n";
//assert(testForDuplicates());
return array[1];
}
public T poll(){
//assert(testForDuplicates());
// assert(queue.size()==size);
if(size==0){return null;}
T t=array[1];
// assert(t==queue.poll());
array[1]=array[size];
array[size]=null;
size--;
if(size>0){percUp(1);}
// assert(queue.size()==size);
// assert(queue.peek()==peek());
//assert(testForDuplicates());
return t;
}
private void percDown(int loc){
//assert(testForDuplicates());
assert(loc>0);
if(loc==1){return;}
int next=loc/2;
T a=array[loc];
T b=array[next];
assert(a!=b);
if(a.compareTo(b)<0){
array[next]=a;
array[loc]=b;
percDown(next);
}
}
private void percUp(int loc){
//assert(testForDuplicates());
assert(loc>0 && loc<=size) : loc+", "+size;
int next1=loc*2;
int next2=next1+1;
if(next1>size){return;}
T a=array[loc];
T b=array[next1];
T c=array[next2];
assert(a!=b);
assert(b!=c);
assert(b!=null);
//assert(testForDuplicates());
if(c==null || b.compareTo(c)<1){
if(a.compareTo(b)>0){
array[next1]=a;
array[loc]=b;
//assert(testForDuplicates());
percUp(next1);
}
}else{
if(a.compareTo(c)>0){
array[next2]=a;
array[loc]=c;
//assert(testForDuplicates());
percUp(next2);
}
}
}
public boolean isEmpty(){
// assert((size==0) == queue.isEmpty());
return size==0;
}
public boolean hasRoom(){
return size<CAPACITY;
}
public void clear(){
// queue.clear();
for(int i=1; i<=size; i++){array[i]=null;}
size=0;
}
public int size(){
return size;
}
public static int tier(int x){
int leading=Integer.numberOfLeadingZeros(x);
return 31-leading;
}
public boolean testForDuplicates(){
for(int i=0; i<array.length; i++){
for(int j=i+1; j<array.length; j++){
if(array[i]!=null && array[i]==array[j]){return false;}
}
}
return true;
}
public ArrayList<T> toList(){
ArrayList<T> list=new ArrayList<T>(size);
for(int i=0, lim=size; i<lim; i++){
list.add(poll());
}
assert(isEmpty());
return list;
}
private final T[] array;
private final int CAPACITY;
private final boolean rollover;
private int size=0;
// private PriorityQueue<T> queue;
}
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