归并排序

主代码

package sort;

/**
 * 归并排序
 * @author potter
 *
 */
public class Guibingsort {

    //low代表数组的第一个数字的下标一般为0；
    //mid代表数组中间点的位置
    //mid+1代表从中间点分开右边数组的第一个位置的下标
    //hight代表数组的最大下标值
    public static void merge(int[] a,int low, int mid, int hight){
        int[] temp = new int[hight - low +1];
        int i = low;
        int j = mid + 1;
        int k = 0;
        //把较小的数移入到新数组中
        while (i <= mid && j <= hight) {
            
            if (a[i] < a[j]) {
                temp[k++] = a[i++];
            }else {
                temp[k++] = a[j++];
            }
        } 
        //把左边剩余的数组移入数组
        while (i <= mid) {

            temp[k++] = a[i++];
        }
        //把右边剩余的数组移入数组
        while (j <= hight) {

            temp[k++] = a[j++];
            
        }
        for(int x = 0;x < temp.length;x++){
            a[x+low] = temp[x];
        }
    }
    public static int[] sort(int[] a,int low,int hight) {
        
        int mid  = (low+hight)/2;
        if (low < hight) {
            sort(a, low, mid);
            sort(a, mid+1, hight);
            merge(a, low, mid, hight);
        }
        return a;
    }
}

随机生成数组

package utilsort;

import java.util.Random;
/**
 * 随机生成数组
 * @author Administrator
 *
 */
public class UtilsSort {

    static Random r = new Random();
    //length代表数组长度
    //min代表可以随机生成数组的最小值
    //max代表可以随机生成数组的最大值
    public static int[]  creat(int length,int min,int max){
        
        if (min > max) {
            int temp = min;
            min = max;
            max = temp;
        }
        int arr[] = new int[length];
        
        for (int i = 0; i < length; i++) {
            int nextInt = r.nextInt(max);
            arr[i] = nextInt + min ;
        }
        return arr;
    }
}

遍历输出类

package utilsort;


public class PrintUtils {

    public static void printarr(int[] arr){
        for (int i : arr) {
            System.out.print(i + " ");
        }
        System.out.println();
    }
}

测试类

package sort;

import utilsort.PrintUtils;
import utilsort.UtilsSort;

public class Testsort {

    public static void main(String[] arg) {
        int[] arr = UtilsSort.creat(5, 1, 33);
        System.out.println("排序前的数列");
        PrintUtils.printarr(arr);
        
        Guibingsort.sort(arr, 0, arr.length-1);
        System.out.println("排序后的数列");
        PrintUtils.printarr(arr);
    }
}