/**
* heap sort
* @author Peter.Yu
*
*/
public class HeapSort {
public static int COUNT = 0;
/**
* build heap
* @param a
* @param size
*/
public static void buildHeap(int[] a, int size) {
for (int i = size / 2; i >= 1; i--) {
adjustHeap(a, i, size);
}
}
/**
* adjust heap
* @param a
* @param i
* @param size
*/
public static void adjustHeap(int[] a, int i, int size) {
int leftChild = i * 2;
int rightChild = i * 2 + 1;
int current = i;
COUNT++;
if (i <= size / 2) {
if (leftChild <= size && a[leftChild] > a[current]) {
current = leftChild;
}
if (rightChild <= size && a[rightChild] > a[current]) {
current = rightChild;
}
if (current != i) {
swap(a, i, current);
adjustHeap(a, current, size);
}
}
}
/**
* swap array element
* @param a
* @param i
* @param j
*/
public static void swap(int[] a, int i, int j) {
int temp = a[i];
a[i] = a[j];
a[j] = temp;
}
/**
* sort heap
* @param a
* @param size
*/
public static void sortHeap(int[] a, int size) {
buildHeap(a, size);
for (int i = size; i >= 1; i--) {
swap(a, 1, i);
adjustHeap(a, 1, i - 1);
}
}
/**
* test
* @param args
*/
public static void main(String[] args) {
int a[] = { 0, 0, 16, 20, 3, 11, 17, 8, 12 };
for (int i = 0; i < a.length; i++) {
System.out.print(a[i] + " ");
}
System.out.println("");
sortHeap(a, a.length - 1);
for (int i = 0; i < a.length; i++) {
System.out.print(a[i] + " ");
}
System.out.println();
System.out.println(COUNT);
}
}
