排序——java

堆排序：

import java.util.Scanner;

public class HeapSort {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("输入n:");
        int n = sc.nextInt();
        int[] a = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = sc.nextInt();
        }
        sort(a);
        for (int i = 0; i < n; i++) {
            System.out.print(a[i] + " ");
        }
    }

    public static void sort(int[] a) {
        int k = a.length / 2 - 1;//堆排序是从最后一个非叶子起点开始的，即为 length / 2 - 1;
        for (int i = k; i >= 0; i--) {
            adjustHeap(a, i, a.length);
        }

        for (int j = a.length - 1; j > 0; j--) {//j > 0 是因为建好堆以后就有了最大值，所以少一次。
            swap(a, 0, j);
            adjustHeap(a, 0, j);
        }
    }

    //堆的特点：左子节点为i*2+1，右子节点为i*2+2；
    public static void adjustHeap(int[] a, int i, int length) {
        int temp = a[i];
        for (int j = 2 * i + 1; j < length; j = j * 2 + 1) {
            if (j + 1 < length && a[j + 1] > a[j]) {//如果右节点比左节点要大的话，直接指向右节点
                j++;
            }
            if (a[j] > temp) {
                a[i] = a[j];
                i = j;
            } else {
                break;//因为下面的已经是排好了的。
            }
        }
        a[i] = temp;
    }

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

希尔排序：

import java.util.Scanner;

public class Shell {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();//输入数组的长度

        int[] data = new int[n + 1];

        for (int i = 1; i <= n; i++) {
            data[i] = sc.nextInt();//赋值
        }

        for (int i = n / 2; i > 0; i /= 2) {
            shellSort(data, i);
        }

        for (int i = 1; i <= n; i++) {
            System.out.print(data[i] + " ");
        }

    }


    public static void shellSort(int[] data, int jg) {
        //插入排序的思想
        for (int i = 1 + jg; i < data.length; i++) {
            if (data[i] < data[i - jg]) {//如果后面的小于前面的
                data[0] = data[i];//先把这个存储起来.
                int j = i - jg;
                do {
                    data[j + jg] = data[j];
                    j = j - jg;
                } while (j > 0 && data[j] > data[0]);
                data[j + jg] = data[0];
            }
        }
    }
}