排序之堆排序

public class HeapSort {    public static void main(String[] args) {        CreateNoOrderArray createNoOrderArray = new CreateNoOrderArray();        int[] array = createNoOrderArray.creat();        System.out.println("Before heap:");        System.out.println(Arrays.toString(array));        heapSort(array);        System.out.println("After heap sort:");        System.out.println(Arrays.toString(array));    }    /**     * 堆排序     * @param array     */    private static void heapSort(int[] array) {        if (array == null || array.length <= 1) {            return;        }        buildMaxHeap(array);        for (int i = array.length - 1; i >= 1; i--) {            swap(array, 0, i);   //每次把最大的换到最后            heapify(array, i, 0);  //重新把次大的调整到根节点        }    }    /**     * 构造最大堆     * @param array     */    private static void buildMaxHeap(int[] array) {        if (array == null || array.length <= 1) {            return;        }        int half = array.length / 2;        for (int i = half; i >= 0; i--) {   //从最后一个节点的父节点开始调整，使根节点是最大的            heapify(array, array.length, i);        }    }    /**     * 从index向下调整     * @param array     * @param heapSize     * @param index     */    private static void heapify(int[] array, int heapSize, int index) {        int left = index * 2 + 1;        int right = index * 2 + 2;        int largest = index;        while(left < heapSize){            if (array[left] > array[index]) {                largest = left;            }            if (right < heapSize && array[right] > array[largest]) {                largest = right;            }            if (index != largest) {                swap(array, index, largest);            }else {                break;            }            index = largest;            left = index * 2 + 1;            right = index * 2 + 2;        }    }    private static void swap(int[] array, int i, int j) {        int temp = array[i];        array[i] = array[j];        array[j] = temp;    }}