选择排序-堆排序

public class HeapSort {

    public static void sort(int[] arr) {

        for (int i = arr.length / 2 - 1; i >= 0; i--) {
            adjustHeap(arr, i, arr.length);
        }

        for (int i = arr.length - 1; i > 0; i--) {
            swap(arr, 0, i);
            adjustHeap(arr, 0, i);
        }

    }

    public static void swap(int[] arr, int a, int b) {
        int temp = arr[a];
        arr[a] = arr[b];
        arr[b] = temp;
    }

    public static void adjustHeap(int[] arr, int i, int length) {
        int temp = arr[i];

        for (int j = i * 2 + 1; j < length; j = j * 2 + 1) {

            if (j + 1 < length && arr[j] < arr[j + 1]) {
                j++;
            }

            if (arr[j] > temp) {
                arr[i] = arr[j];
                i = j;
            } else {
                break;
            }

            arr[i] = temp;
        }

    }

    public static void main(String[] args) {
        int[] arr = new int[] { 9, 8, 7, 6, 5, 4, 3, 2, 1 };
        sort(arr);
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i]);
            System.out.print(" ");
        }
    }
}