org.jheaps.array.AbstractBinaryArrayDoubleEndedHeap Maven / Gradle / Ivy
package org.jheaps.array;
import java.io.Serializable;
import java.util.Comparator;
import java.util.NoSuchElementException;
import org.jheaps.DoubleEndedHeap;
import org.jheaps.annotations.VisibleForTesting;
/**
* Abstract implementation of a binary double-ended heap using an array
* representation.
*
* @author Dimitrios Michail
*
* @param
* the type of keys maintained by this heap
*/
abstract class AbstractBinaryArrayDoubleEndedHeap extends AbstractArrayHeap
implements DoubleEndedHeap, Serializable {
private static final long serialVersionUID = 1L;
/**
* Constructor
*
* @param comparator
* the comparator to use
* @param capacity
* the requested capacity
*/
public AbstractBinaryArrayDoubleEndedHeap(Comparator comparator, int capacity) {
super(comparator, capacity);
}
/**
* {@inheritDoc}
*/
@Override
@SuppressWarnings("unchecked")
public K findMax() {
switch (size) {
case 0:
throw new NoSuchElementException();
case 1:
return array[1];
case 2:
return array[2];
default:
if (comparator == null) {
if (((Comparable) array[3]).compareTo(array[2]) > 0) {
return array[3];
} else {
return array[2];
}
} else {
if (comparator.compare(array[3], array[2]) > 0) {
return array[3];
} else {
return array[2];
}
}
}
}
/**
* {@inheritDoc}
*/
@Override
@SuppressWarnings("unchecked")
public K deleteMax() {
K result;
switch (size) {
case 0:
throw new NoSuchElementException();
case 1:
result = array[1];
array[1] = null;
size--;
break;
case 2:
result = array[2];
array[2] = null;
size--;
break;
default:
result = array[2];
if (comparator == null) {
if (((Comparable) array[3]).compareTo(array[2]) > 0) {
result = array[3];
array[3] = array[size];
array[size] = null;
size--;
if (size >= 3) {
fixdownMax(3);
}
} else {
result = array[2];
array[2] = array[size];
array[size] = null;
size--;
fixdownMax(2);
}
} else {
if (comparator.compare(array[3], array[2]) > 0) {
result = array[3];
array[3] = array[size];
array[size] = null;
size--;
if (size >= 3) {
fixdownMaxWithComparator(3);
}
} else {
result = array[2];
array[2] = array[size];
array[size] = null;
size--;
fixdownMaxWithComparator(2);
}
}
break;
}
if (DOWNSIZING_MIN_HEAP_CAPACITY < array.length - 1 && 4 * size < array.length - 1) {
ensureCapacity((array.length - 1) / 2 + 1);
}
return result;
}
/**
* Upwards fix starting from a particular element
*
* @param k
* the index of the starting element
*/
@Override
@SuppressWarnings("unchecked")
protected void fixup(int k) {
if (onMinLevel(k)) {
int p = k / 2;
K kValue = array[k];
if (p > 0 && ((Comparable) array[p]).compareTo(kValue) < 0) {
array[k] = array[p];
array[p] = kValue;
fixupMax(p);
} else {
fixupMin(k);
}
} else {
int p = k / 2;
K kValue = array[k];
if (p > 0 && ((Comparable) kValue).compareTo(array[p]) < 0) {
array[k] = array[p];
array[p] = kValue;
fixupMin(p);
} else {
fixupMax(k);
}
}
}
/**
* Upwards fix starting from a particular element
*
* @param k
* the index of the starting element
*/
protected void fixupWithComparator(int k) {
if (onMinLevel(k)) {
int p = k / 2;
K kValue = array[k];
if (p > 0 && comparator.compare(array[p], kValue) < 0) {
array[k] = array[p];
array[p] = kValue;
fixupMaxWithComparator(p);
} else {
fixupMinWithComparator(k);
}
} else {
int p = k / 2;
K kValue = array[k];
if (p > 0 && comparator.compare(kValue, array[p]) < 0) {
array[k] = array[p];
array[p] = kValue;
fixupMinWithComparator(p);
} else {
fixupMaxWithComparator(k);
}
}
}
/**
* Upwards fix starting from a particular element at a minimum level
*
* @param k
* the index of the starting element
*/
@SuppressWarnings("unchecked")
private void fixupMin(int k) {
K key = array[k];
int gp = k / 4;
while (gp > 0 && ((Comparable) array[gp]).compareTo(key) > 0) {
array[k] = array[gp];
k = gp;
gp = k / 4;
}
array[k] = key;
}
/**
* Upwards fix starting from a particular element at a minimum level.
* Performs comparisons using the comparator.
*
* @param k
* the index of the starting element
*/
private void fixupMinWithComparator(int k) {
K key = array[k];
int gp = k / 4;
while (gp > 0 && comparator.compare(array[gp], key) > 0) {
array[k] = array[gp];
k = gp;
gp = k / 4;
}
array[k] = key;
}
/**
* Upwards fix starting from a particular element at a maximum level
*
* @param k
* the index of the starting element
*/
@SuppressWarnings("unchecked")
private void fixupMax(int k) {
K key = array[k];
int gp = k / 4;
while (gp > 0 && ((Comparable) array[gp]).compareTo(key) < 0) {
array[k] = array[gp];
k = gp;
gp = k / 4;
}
array[k] = key;
}
/**
* Upwards fix starting from a particular element at a maximum level.
* Performs comparisons using the comparator.
*
* @param k
* the index of the starting element
*/
private void fixupMaxWithComparator(int k) {
K key = array[k];
int gp = k / 4;
while (gp > 0 && comparator.compare(array[gp], key) < 0) {
array[k] = array[gp];
k = gp;
gp = k / 4;
}
array[k] = key;
}
/**
* Downwards fix starting from a particular element.
*
* @param k
* the index of the starting element
*/
@Override
protected void fixdown(int k) {
if (onMinLevel(k)) {
fixdownMin(k);
} else {
fixdownMax(k);
}
}
/**
* Downwards fix starting from a particular element. Performs comparisons
* using the comparator.
*
* @param k
* the index of the starting element
*/
@Override
protected void fixdownWithComparator(int k) {
if (onMinLevel(k)) {
fixdownMinWithComparator(k);
} else {
fixdownMaxWithComparator(k);
}
}
/**
* Downwards fix starting from a particular element at a minimum level.
*
* @param k
* the index of the starting element
*/
@SuppressWarnings("unchecked")
private void fixdownMin(int k) {
int c = 2 * k;
while (c <= size) {
int m = minChildOrGrandchild(k);
if (m > c + 1) { // grandchild
if (((Comparable) array[m]).compareTo(array[k]) >= 0) {
break;
}
K tmp = array[k];
array[k] = array[m];
array[m] = tmp;
if (((Comparable) array[m]).compareTo(array[m / 2]) > 0) {
tmp = array[m];
array[m] = array[m / 2];
array[m / 2] = tmp;
}
// go down
k = m;
c = 2 * k;
} else { // child
if (((Comparable) array[m]).compareTo(array[k]) < 0) {
K tmp = array[k];
array[k] = array[m];
array[m] = tmp;
}
break;
}
}
}
/**
* Downwards fix starting from a particular element at a minimum level.
* Performs comparisons using the comparator.
*
* @param k
* the index of the starting element
*/
private void fixdownMinWithComparator(int k) {
int c = 2 * k;
while (c <= size) {
int m = minChildOrGrandchildWithComparator(k);
if (m > c + 1) { // grandchild
if (comparator.compare(array[m], array[k]) >= 0) {
break;
}
K tmp = array[k];
array[k] = array[m];
array[m] = tmp;
if (comparator.compare(array[m], array[m / 2]) > 0) {
tmp = array[m];
array[m] = array[m / 2];
array[m / 2] = tmp;
}
// go down
k = m;
c = 2 * k;
} else { // child
if (comparator.compare(array[m], array[k]) < 0) {
K tmp = array[k];
array[k] = array[m];
array[m] = tmp;
}
break;
}
}
}
/**
* Downwards fix starting from a particular element at a maximum level.
*
* @param k
* the index of the starting element
*/
@SuppressWarnings("unchecked")
private void fixdownMax(int k) {
int c = 2 * k;
while (c <= size) {
int m = maxChildOrGrandchild(k);
if (m > c + 1) { // grandchild
if (((Comparable) array[m]).compareTo(array[k]) <= 0) {
break;
}
K tmp = array[k];
array[k] = array[m];
array[m] = tmp;
if (((Comparable) array[m]).compareTo(array[m / 2]) < 0) {
tmp = array[m];
array[m] = array[m / 2];
array[m / 2] = tmp;
}
// go down
k = m;
c = 2 * k;
} else { // child
if (((Comparable) array[m]).compareTo(array[k]) > 0) {
K tmp = array[k];
array[k] = array[m];
array[m] = tmp;
}
break;
}
}
}
/**
* Downwards fix starting from a particular element at a maximum level.
* Performs comparisons using the comparator.
*
* @param k
* the index of the starting element
*/
private void fixdownMaxWithComparator(int k) {
int c = 2 * k;
while (c <= size) {
int m = maxChildOrGrandchildWithComparator(k);
if (m > c + 1) { // grandchild
if (comparator.compare(array[m], array[k]) <= 0) {
break;
}
K tmp = array[k];
array[k] = array[m];
array[m] = tmp;
if (comparator.compare(array[m], array[m / 2]) < 0) {
tmp = array[m];
array[m] = array[m / 2];
array[m / 2] = tmp;
}
// go down
k = m;
c = 2 * k;
} else { // child
if (comparator.compare(array[m], array[k]) > 0) {
K tmp = array[k];
array[k] = array[m];
array[m] = tmp;
}
break;
}
}
}
/**
* Return true if on a minimum level, false otherwise.
*
* @param k
* the element
* @return true if on a minimum level, false otherwise
*/
@VisibleForTesting
boolean onMinLevel(int k) {
float kAsFloat = k;
int exponent = Math.getExponent(kAsFloat);
return exponent % 2 == 0;
}
/**
* Given a node at a maximum level, find its child or grandchild with the
* maximum key. This method should not be called for a node which has no
* children.
*
* @param k
* a node at a maximum level
* @return the child or grandchild with a maximum key, or undefined if there
* are no children
*/
@SuppressWarnings("unchecked")
private int maxChildOrGrandchild(int k) {
int gc = 4 * k;
int maxgc;
K gcValue;
// 4 grandchilden
if (gc + 3 <= size) {
gcValue = array[gc];
maxgc = gc;
if (((Comparable) array[++gc]).compareTo(gcValue) > 0) {
gcValue = array[gc];
maxgc = gc;
}
if (((Comparable) array[++gc]).compareTo(gcValue) > 0) {
gcValue = array[gc];
maxgc = gc;
}
if (((Comparable) array[++gc]).compareTo(gcValue) > 0) {
maxgc = gc;
}
return maxgc;
}
// less or equal to 3
switch (size - gc) {
case 2:
// 3 grandchildren, two children
gcValue = array[gc];
maxgc = gc;
if (((Comparable) array[++gc]).compareTo(gcValue) > 0) {
gcValue = array[gc];
maxgc = gc;
}
if (((Comparable) array[++gc]).compareTo(gcValue) > 0) {
maxgc = gc;
}
return maxgc;
case 1:
// 2 grandchildren, maybe two children
gcValue = array[gc];
maxgc = gc;
if (((Comparable) array[++gc]).compareTo(gcValue) > 0) {
gcValue = array[gc];
maxgc = gc;
}
if (2 * k + 1 <= size && ((Comparable) array[2 * k + 1]).compareTo(gcValue) > 0) {
maxgc = 2 * k + 1;
}
return maxgc;
case 0:
// 1 grandchild, maybe two children
gcValue = array[gc];
maxgc = gc;
if (2 * k + 1 <= size && ((Comparable) array[2 * k + 1]).compareTo(gcValue) > 0) {
maxgc = 2 * k + 1;
}
return maxgc;
}
// 0 grandchildren
maxgc = 2 * k;
gcValue = array[maxgc];
if (2 * k + 1 <= size && ((Comparable) array[2 * k + 1]).compareTo(gcValue) > 0) {
maxgc = 2 * k + 1;
}
return maxgc;
}
/**
* Given a node at a maximum level, find its child or grandchild with the
* maximum key. This method should not be called for a node which has no
* children.
*
* @param k
* a node at a maximum level
* @return the child or grandchild with a maximum key, or undefined if there
* are no children
*/
private int maxChildOrGrandchildWithComparator(int k) {
int gc = 4 * k;
int maxgc;
K gcValue;
// 4 grandchilden
if (gc + 3 <= size) {
gcValue = array[gc];
maxgc = gc;
if (comparator.compare(array[++gc], gcValue) > 0) {
gcValue = array[gc];
maxgc = gc;
}
if (comparator.compare(array[++gc], gcValue) > 0) {
gcValue = array[gc];
maxgc = gc;
}
if (comparator.compare(array[++gc], gcValue) > 0) {
maxgc = gc;
}
return maxgc;
}
// less or equal to 3
switch (size - gc) {
case 2:
// 3 grandchildren, two children
gcValue = array[gc];
maxgc = gc;
if (comparator.compare(array[++gc], gcValue) > 0) {
gcValue = array[gc];
maxgc = gc;
}
if (comparator.compare(array[++gc], gcValue) > 0) {
maxgc = gc;
}
return maxgc;
case 1:
// 2 grandchildren, maybe two children
gcValue = array[gc];
maxgc = gc;
if (comparator.compare(array[++gc], gcValue) > 0) {
gcValue = array[gc];
maxgc = gc;
}
if (2 * k + 1 <= size && comparator.compare(array[2 * k + 1], gcValue) > 0) {
maxgc = 2 * k + 1;
}
return maxgc;
case 0:
// 1 grandchild, maybe two children
gcValue = array[gc];
maxgc = gc;
if (2 * k + 1 <= size && comparator.compare(array[2 * k + 1], gcValue) > 0) {
maxgc = 2 * k + 1;
}
return maxgc;
}
// 0 grandchildren
maxgc = 2 * k;
gcValue = array[maxgc];
if (2 * k + 1 <= size && comparator.compare(array[2 * k + 1], gcValue) > 0) {
maxgc = 2 * k + 1;
}
return maxgc;
}
/**
* Given a node at a minimum level, find its child or grandchild with the
* minimum key. This method should not be called for a node which has no
* children.
*
* @param k
* a node at a minimum level
* @return the child or grandchild with a minimum key, or undefined if there
* are no children
*/
@SuppressWarnings("unchecked")
private int minChildOrGrandchild(int k) {
int gc = 4 * k;
int mingc;
K gcValue;
// 4 grandchilden
if (gc + 3 <= size) {
gcValue = array[gc];
mingc = gc;
if (((Comparable) array[++gc]).compareTo(gcValue) < 0) {
gcValue = array[gc];
mingc = gc;
}
if (((Comparable) array[++gc]).compareTo(gcValue) < 0) {
gcValue = array[gc];
mingc = gc;
}
if (((Comparable) array[++gc]).compareTo(gcValue) < 0) {
mingc = gc;
}
return mingc;
}
// less or equal to 3
switch (size - gc) {
case 2:
// 3 grandchildren, two children
gcValue = array[gc];
mingc = gc;
if (((Comparable) array[++gc]).compareTo(gcValue) < 0) {
gcValue = array[gc];
mingc = gc;
}
if (((Comparable) array[++gc]).compareTo(gcValue) < 0) {
mingc = gc;
}
return mingc;
case 1:
// 2 grandchildren, maybe two children
gcValue = array[gc];
mingc = gc;
if (((Comparable) array[++gc]).compareTo(gcValue) < 0) {
gcValue = array[gc];
mingc = gc;
}
if (2 * k + 1 <= size && ((Comparable) array[2 * k + 1]).compareTo(gcValue) < 0) {
mingc = 2 * k + 1;
}
return mingc;
case 0:
// 1 grandchild, maybe two children
gcValue = array[gc];
mingc = gc;
if (2 * k + 1 <= size && ((Comparable) array[2 * k + 1]).compareTo(gcValue) < 0) {
mingc = 2 * k + 1;
}
return mingc;
}
// 0 grandchildren
mingc = 2 * k;
gcValue = array[mingc];
if (2 * k + 1 <= size && ((Comparable) array[2 * k + 1]).compareTo(gcValue) < 0) {
mingc = 2 * k + 1;
}
return mingc;
}
/**
* Given a node at a minimum level, find its child or grandchild with the
* minimum key. This method should not be called for a node which has no
* children.
*
* @param k
* a node at a minimum level
* @return the child or grandchild with a minimum key, or undefined if there
* are no children
*/
private int minChildOrGrandchildWithComparator(int k) {
int gc = 4 * k;
int mingc;
K gcValue;
// 4 grandchilden
if (gc + 3 <= size) {
gcValue = array[gc];
mingc = gc;
if (comparator.compare(array[++gc], gcValue) < 0) {
gcValue = array[gc];
mingc = gc;
}
if (comparator.compare(array[++gc], gcValue) < 0) {
gcValue = array[gc];
mingc = gc;
}
if (comparator.compare(array[++gc], gcValue) < 0) {
mingc = gc;
}
return mingc;
}
// less or equal to 3
switch (size - gc) {
case 2:
// 3 grandchildren, two children
gcValue = array[gc];
mingc = gc;
if (comparator.compare(array[++gc], gcValue) < 0) {
gcValue = array[gc];
mingc = gc;
}
if (comparator.compare(array[++gc], gcValue) < 0) {
mingc = gc;
}
return mingc;
case 1:
// 2 grandchildren, maybe two children
gcValue = array[gc];
mingc = gc;
if (comparator.compare(array[++gc], gcValue) < 0) {
gcValue = array[gc];
mingc = gc;
}
if (2 * k + 1 <= size && comparator.compare(array[2 * k + 1], gcValue) < 0) {
mingc = 2 * k + 1;
}
return mingc;
case 0:
// 1 grandchild, maybe two children
gcValue = array[gc];
mingc = gc;
if (2 * k + 1 <= size && comparator.compare(array[2 * k + 1], gcValue) < 0) {
mingc = 2 * k + 1;
}
return mingc;
}
// 0 grandchildren
mingc = 2 * k;
gcValue = array[mingc];
if (2 * k + 1 <= size && comparator.compare(array[2 * k + 1], gcValue) < 0) {
mingc = 2 * k + 1;
}
return mingc;
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy