Java八大基本排序之堆排序

Posted 2021-03-07 误入IT界的农民工

public class SortHeap {


    public static void sort(int[] data) {

        // 构建大顶堆
        for (int i = (data.length - 2) / 2; i >= 0; i--) {
            adjustHeap(data, i, data.length);
        }

        // 对顶元素与堆尾元素进行调整，重现调整堆为大顶堆
        for (int j = data.length - 1; j >= 0; j--) {
            int temp = data[j];
            data[j] = data[0];
            data[0] = temp;
            adjustHeap(data, 0, j);
        }
    }

    public static void adjustHeap(int[] data, int i, int length) {
        int temp = data[i];
        for (int k = i * 2 + 1; k < length; k = k * 2 + 1) {
            if (k + 1 < length && data[k] < data[k + 1]) { // 比较左孩子是否小于右孩子，如果小于，则直接比较右孩子
                k++;
            }
            if (data[k] > temp) {
                data[i] = data[k];
                i = k;
            } else {
                break;
            }
        }
        data[i] = temp;
    }


    public static void main(String[] args) {

        int data[] = {4, 5, 8, 1, 2, 3, 6, 7, 11, 10, 9};

        for (int i = 0; i < data.length; i++) {
            System.out.print(data[i] + "  ");
        }
        System.out.println();
        System.out.println("-----------------------------");

        sort(data);
        for (int i = 0; i < data.length; i++) {
            System.out.print(data[i] + "  ");
        }
        System.out.println();
    }


}

输出如下：
4  5  8  1  2  3  6  7  11  10  9  
-----------------------------
1  2  3  4  5  6  7  8  9  10  11  

Process finished with exit code 0