堆排序

    /**     * TODO 维护最大堆      * @param arr     * @param i     * @param length     */    private static void maxHeapify(int[] arr,int i,int length){int leftIndex = 2*i+1;int rightIndex = 2*(i+1);int largestIndex = i;if(leftIndex<length && arr[i]<arr[leftIndex]){    largestIndex = leftIndex;}if(rightIndex<length && arr[largestIndex]<arr[rightIndex]){    largestIndex = rightIndex;}if(largestIndex!=i){    swap(arr,i,largestIndex);    maxHeapify(arr,largestIndex,length);}    }        /**     * TODO 交换两个数据的值      * @param arr     * @param i     * @param largestIndex     */    private static void swap(int[] arr, int i, int largestIndex) {int temp = arr[i];arr[i] = arr[largestIndex];arr[largestIndex] = temp;    }        /**     * TODO 建堆     * @param arr     */    private static void buildMaxHeap(int[] arr){for(int i=arr.length/2-1;i>=0;i--){    maxHeapify(arr,i,arr.length);}    }        /**     * TODO 排序      * @param arr     */    public static void heapSort(int[] arr){buildMaxHeap(arr);for(int i=arr.length-1;i>0;i--){    swap(arr,i,0);    maxHeapify(arr,0,i);}    }