堆排序

Posted 2020-10-19 weishao-lsv

 

   public static int[] heapSort(int[] arr) {
        int i;
        for (i = arr.length / 2; i >= 0; i--) {
            heapAdjust(arr, i, arr.length - 1);
        }
        for (i = arr.length - 1; i > 0; i--){
            swap(arr, 0, i);
            heapAdjust(arr, 0, i - 1);
        }
        return arr;
    }

    private static void heapAdjust(int[] arr, int s, int m) {
        int temp, j;
        temp = arr[s];  
        for (j = 2 * s; j <= m; j *= 2){
            // 如果右节点比左节点大,当前节点移到右节点
            if (j < m && arr[j] < arr[j + 1]){
                // 指向右节点
                j++;
            }
            if (temp >= arr[j]){
                break;
            }
            arr[s] = arr[j];
            s = j;
        }
        arr[s] = temp;
    }
    private static void swap(int[] arr, int heigh, int low) {
        int temp = arr[heigh];
        arr[heigh] = arr[low];
        arr[low] = temp;
    }