數據結構堆排序的代碼

感覺比網上的大多數方法都好

 
    @Test
    public void testMaxHeap(){
        int[] sourceArray = {16,7,3,20,17,8};
        buildMaxHeap(sourceArray);
        System.out.println(sourceArray);


        int[] sourceArrayTwo = {16,7,3,2,-7,-8};
        buildMaxHeap(sourceArrayTwo);
        System.out.println(sourceArrayTwo);
    }

    private void buildMaxHeap(int[] arr) {
        int len = arr.length;
        for (int i=0;i<len;i++) {
            for (int j = (len-i) / 2 -1; j >= 0; j--) {
                heapify(arr, j, len-i);
            }
            swap(arr,0,len-i-1);
        }
    }

    private void heapify(int[] arr, int i, int len) {
        int left = 2 * i + 1;
        int right = 2 * i + 2;
        int largest = i;

        if (left < len && arr[left] > arr[largest]) {
            largest = left;
        }

        if (right < len && arr[right] > arr[largest]) {
            largest = right;
        }
        swap(arr, i, largest);
    }

    private void swap(int[] arr, int i, int j) {
        if (i==j) {return;}
        arr[i] =arr[i] ^arr[j];
        arr[j] = arr[i]^arr[j];
        arr[i] = arr[i]^arr[j];
    }