堆排序详细解说

    public static void heapSort(int[] array){
        creatHeap(array);
        for (int i = 0; i < array.length-1; i++){
            exchange(array,0,array.length - 1 -i);

            shiftDown(array, array.length -1 -i, 0);

        }
    }
    public static void shiftDown(int[] array, int size, int index){
        //向下调整  大堆!!!!!
        int parent = index;
        int child = 2*parent + 1;
        while (child < size){
            if (child + 1 < size && array[child+1] > array[child]){
                child = child+1;
            }
            if (array[child] > array[parent]){
                exchange(array,child,parent);
            }else {
                break;
            }
            parent = child;
            child = 2 * parent + 1;
        }
    }

    private static void creatHeap(int[] array) {
        for (int i = (array.length - 1 - 1)/2; i >= 0; i--){
            shiftDown(array,array.length,i);
        }
    }


    private static void exchange(int[] array, int bound, int cur) {
        int tmp = array[bound];
        array[bound] = array[cur];
        array[cur] = tmp;
    }