快速排序、归并排序

感觉好久之前不写这些基础的东西忽然觉着，想复习一下，就简单温习一下排序的例子

package com.ruishenh.algoritmic;public class Sort {public static void main(String[] args) {// 冒泡排序int[] arrs=getRandomArrs(20000);//printMsg(arrs);long start = System.currentTimeMillis();bubblingSort(arrs);long end = System.currentTimeMillis();//printMsg(arrs);System.out.println("冒泡结果："+(end - start));System.out.println("----------------------");// 归并排序arrs = getRandomArrs(5000000);start = System.currentTimeMillis();mergerSort(arrs);end = System.currentTimeMillis();System.out.println("归并结果："+(end - start));System.out.println("----------------------");// 快排排序arrs = getRandomArrs(5000000);start = System.currentTimeMillis();quickSort(arrs,0,arrs.length-1);end = System.currentTimeMillis();System.out.println("快排结果："+(end - start));System.out.println("----------------------");}static void printMsg(int [] arrs){for (int i : arrs) {System.out.print(i);System.out.print(",");}System.out.println();}static int [] getRandomArrs(int num){int [] ret=new int[num];for (int i = 0; i < num; i++) {ret[i]=(int) Math.floor(Math.random()*num);}return ret;};/** * 冒泡排序 * @param arrs */static void bubblingSort(int [] arrs){for (int i = 0; i < arrs.length; i++) {for (int j = 0; j < arrs.length-1-i; j++) {if (arrs[j]>arrs[j+1]) {int tmp=arrs[j];arrs[j]=arrs[j+1];arrs[j+1]=tmp;}}}}/** * 归并排序 * @param arrs */static void mergerSort(int [] arrs){mergerSort_split(arrs, 0, arrs.length-1, new int[arrs.length]);}static void mergerSort_merge(int [] a,int first,int mid,int last, int []  temp){{      int i = first, j = mid + 1;      int m = mid,   n = last;      int k = 0;            while (i <= m && j <= n)      {          if (a[i] <= a[j])              temp[k++] = a[i++];          else              temp[k++] = a[j++];      }            while (i <= m)          temp[k++] = a[i++];            while (j <= n)          temp[k++] = a[j++];            for (i = 0; i < k; i++)          a[first + i] = temp[i];  }  }static void mergerSort_split(int [] arrs,int first,int last, int []  temp){ if (first < last)      {          int mid = (first + last) / 2;         //递归循环调用执行对半合并        mergerSort_split(arrs, first, mid, temp);    //左边有序          mergerSort_split(arrs, mid + 1, last, temp); //右边有序          mergerSort_merge(arrs, first, mid, last, temp); //再将二个有序数列合并      }  }    /**     * 快速排序     * @param list     * @param low     * @param high     * @return     */    private static int[] quickSort(int [] list,int low ,int high){        if(low<high){            int middle=getMiddle(list, low, high); //将list数组进行一分为二            quickSort(list, low, middle-1);       //对比key小的进行递归排序            quickSort(list, middle+1, high);      //对比key大的进行递归排序        }        return list;    }    private static int getMiddle(int [] list,int low,int high){        int tmp=list[low];          //数组第一个作为key        while(low<high){            while(low<high&&list[high]>=tmp){                high--;            }            list[low]=list[high];   //比key小的纪录移到低端            while(low<high&&list[low]<=tmp){                low++;            }            list[high]=list[low];  //比key大的纪录移到高端        }        list[low]=tmp;              //key纪录到末尾        return low;                 //返回key的位置    }}

打印结果

冒泡结果：679----------------------归并结果：840----------------------快排结果：504----------------------

冒泡的速度确实不敢说什么了，哈哈 2万多的数据就跑了679，而归并500万才跑了840，快排504