堆排序

public class HeapSort {    public static void main(String[] args) {         int[] array = { 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, -1, -2, -3 };          heapSort(array);         for(int a : array){             System.out.println(a);         }    }    /**     * 堆排序     * @param array     */    public static void heapSort(int array[]){        if(array==null || array.length<=1){            return;        }        buildMaxHeap(array);        for(int i = array.length-1;i>=0;i--){            swap(array,0,i);            maxHeap(array,i,0);        }    }    /**     * 构建最大堆     * @param array     */    public static void buildMaxHeap(int array[]){        if(array==null || array.length<=1){            return;        }        for(int i = (array.length/2);i>=0;i--){            maxHeap(array,array.length,i);        }    }    /**     * 维护最大堆     * @param array     * @param heapSize     * @param index     */    public static void maxHeap(int array[],int heapSize,int index){        int leftChild = 2*index+1;        int rightChild = 2*index+2;        int largest = index;        if( leftChild < heapSize&&array[leftChild] > array[index] ){            largest = leftChild;        }        if(rightChild < heapSize && array[rightChild] > array[largest] ){            largest = rightChild;        }        if(largest != index){            swap(array, largest, index);            maxHeap(array, heapSize, largest);        }    }    public static void swap(int array[],int i,int j){        int temp = array[i];        array[i] = array[j];        array[j] = temp;    }}