堆排序实例(Java数组实现)

public class MaxHeap<T extends Comparable<? super T>> { private T[] data; private int size; private int capacity;  public MaxHeap(int capacity) {  this.data = (T[]) new Comparable[capacity + 1];  size = 0;  this.capacity = capacity; }  public int size() {  return this.size; }  public boolean isEmpty() {  return size == 0; }  public int getCapacity() {  return this.capacity; }  /**  * @return 查看最大根(只看不删, 与popMax对比)  */ public T seekMax() {  return data[1]; }  public void swap(int i, int j) {  if (i != j) {   T temp = data[i];   data[i] = data[j];   data[j] = temp;  } }  public void insert(T item) {  size++;  data[size] = item;  shiftUp(size); }  /**  * @return 弹出最大根(弹出意味着删除, 与seekMax对比)  */ public T popMax() {  swap(1, size--);  shiftDown(1);  return data[size + 1]; }  /**  * @param child 孩子节点下角标是child，父节点下角表是child/2  */ public void shiftUp(int child) {  while (child > 1 && data[child].compareTo(data[child / 2]) > 0) {   swap(child, child / 2);   child = child / 2;  } }  /**  * @param a data数组中某个元素的下角标  * @param b data数组中某个元素的下角标  * @return 哪个元素大就返回哪个的下角标  */ private int max(int a, int b) {  if (data[a].compareTo(data[b]) < 0) {//如果data[b]大   return b;//返回b  } else {//如果data[a]大   return a;//返回a  } }  /**  * @param a data数组中某个元素的下角标  * @param b data数组中某个元素的下角标  * @param c data数组中某个元素的下角标  * @return 哪个元素大就返回哪个的下角标  */ private int max(int a, int b, int c) {  int biggest = max(a, b);  biggest = max(biggest, c);  return biggest; }   /**  * @param father 父节点下角标是father,左右两个孩子节点的下角表分别是：father*2 和 father*2+1  */ public void shiftDown(int father) {  while (true) {   int lchild = father * 2;//左孩子   int rchild = father * 2 + 1;//右孩子   int newFather = father;//newFather即将更新，父、左、右三个结点谁大，newFather就是谁的下角标    if (lchild > size) {//如果该father结点既没有左孩子，也没有右孩子    return;   } else if (rchild > size) {//如果该father结点只有左孩子，没有右孩子    newFather = max(father, lchild);   } else {//如果该father结点既有左孩子，又有右孩子    newFather = max(father, lchild, rchild);   }    if (newFather == father) {//说明father比两个子结点都要大，表名已经是大根堆，不用继续调整了    return;   } else {//否则，还需要继续调整堆，直到满足大根堆条件为止    swap(father, newFather);//值进行交换    father = newFather;//更新father的值，相当于继续调整shiftDown(newFather)   }  } }  public static <T extends Comparable<? super T>> void sort(T[] arr) {  int len = arr.length;  //入堆  MaxHeap<T> maxHeap = new MaxHeap<T>(len);  for (int i = 0; i < len; i++) {   maxHeap.insert(arr[i]);  }  //出堆  for (int i = len - 1; i >= 0; i--) {   arr[i] = maxHeap.popMax();  } }  public static void printArr(Object[] arr) {  for (Object o : arr) {   System.out.print(o);   System.out.print("/t");  }  System.out.println(); }  public static void main(String args[]) {  Integer[] arr = {3, 5, 1, 7, 2, 9, 8, 0, 4, 6};  printArr(arr);//3 5 1 7 2 9 8 0 4 6  sort(arr);  printArr(arr);//0 1 2 3 4 5 6 7 8 9 }}

public class MaxHeap<T extends Comparable<? super T>> { private T[] data; private int size; private int capacity;  public MaxHeap(int capacity) {  this.capacity = capacity;  this.size = 0;  this.data = (T[]) new Comparable[capacity + 1]; }  public MaxHeap(T[] arr) {//heapify,数组建堆  capacity = arr.length;  data = (T[]) new Comparable[capacity + 1];  System.arraycopy(arr, 0, data, 1, arr.length);  size = arr.length;  for (int i = size / 2; i >= 1; i--) {   shiftDown(i);  } }  public int size() {  return this.size; }  public int getCapacity() {  return this.capacity; }  public boolean isEmpty() {  return size == 0; }  public T seekMax() {  return data[1]; }  public void swap(int i, int j) {  if (i != j) {   T temp = data[i];   data[i] = data[j];   data[j] = temp;  } }  public void insert(T item) {  size++;  data[size] = item;  shiftUp(size); }  public T popMax() {  swap(1, size--);  shiftDown(1);  return data[size + 1]; }  public void shiftUp(int child) {  while (child > 1 && data[child].compareTo(data[child / 2]) > 0) {   swap(child, child / 2);   child /= 2;  } }  /**  * @param a data数组中某个元素的下角标  * @param b data数组中某个元素的下角标  * @return 哪个元素大就返回哪个的下角标  */ private int max(int a, int b) {  if (data[a].compareTo(data[b]) < 0) {//如果data[b]大   return b;//返回b  } else {//如果data[a]大   return a;//返回a  } }  /**  * @param a data数组中某个元素的下角标  * @param b data数组中某个元素的下角标  * @param c data数组中某个元素的下角标  * @return 哪个元素大就返回哪个的下角标  */ private int max(int a, int b, int c) {  int biggest = max(a, b);  biggest = max(biggest, c);  return biggest; }  public void shiftDown(int father) {  while (true) {   int lchild = father * 2;   int rchild = father * 2 + 1;   int newFather = father;//这里赋不赋值无所谓，如果把下面这个return改成break,那就必须赋值了    if (lchild > size) {//如果没有左、右孩子    return;   } else if (rchild > size) {//如果没有右孩子    newFather = max(father, lchild);   } else {//如果有左、右孩子    newFather = max(father, lchild, rchild);   }    if (newFather == father) {//如果原父结点就是三者最大，则不用继续整理堆了    return;   } else {//父节点不是最大，则把大的孩子交换上来，然后继续往下堆调整，直到满足大根堆为止    swap(newFather, father);    father = newFather;//相当于继续shiftDown(newFather)。假如newFather原来是father的左孩子，那就相当于shiftDown(2*father)   }  } }  public static <T extends Comparable<? super T>> void sort(T[] arr) {  int len = arr.length;  MaxHeap<T> maxHeap = new MaxHeap<>(arr);  for (int i = len - 1; i >= 0; i--) {   arr[i] = maxHeap.popMax();  } }  public static void printArr(Object[] arr) {  for (Object o : arr) {   System.out.print(o);   System.out.print("/t");  }  System.out.println(); }  public static void main(String args[]) {  Integer[] arr = {3, 5, 1, 7, 2, 9, 8, 0, 4, 6};  printArr(arr);//3 5 1 7 2 9 8 0 4 6  sort(arr);  printArr(arr);//0 1 2 3 4 5 6 7 8 9 }}