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Java程序员必须掌握的8大排序算法

 2015/1/26 3:49:47  gghsfuyi68615  程序员俱乐部  我要评论(0)
  • 摘要:SpringMVC+mybatisHTML5全新高大尚后台框架_集成代码生成器8种排序之间的关系:1,直接插入排序(1)基本思想:在要排序的一组数中,假设前面(n-1)[n>=2]个数已经是排好顺序的,现在要把第n个数插到前面的有序数中,使得这n个数也是排好顺序的。如此反复循环,直到全部排好顺序。(2)实例(3)用java实现?packagecom.njue;publicclassinsertSort{publicinsertSort(){inta[]={49,38,65,97,76
  • 标签:程序 程序员 Java 算法

SpringMVC+mybatis HTML5 全新高大尚后台框架_集成代码生成器

8种排序之间的关系:

1,?直接插入排序

(1)基本思想:在要排序的一组数中,假设前面(n-1)[n>=2] 个数已经是排

好顺序的,现在要把第n个数插到前面的有序数中,使得这n个数

也是排好顺序的。如此反复循环,直到全部排好顺序。

(2)实例

(3)用java实现

? class="java keyword">package com.njue;? ? public class insertSort {? public insertSort(){? ????inta[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51};? ????int temp=0;? ????for(int i=1;i<a.length;i++){? ???????int j=i-1;? ???????temp=a[i];? ???????for(;j>=0&&temp<a[j];j--){? ???????a[j+1]=a[j];?????????????????????? //将大于temp的值整体后移一个单位? ???????}? ???????a[j+1]=temp;? ????}? ????for(int i=0;i<a.length;i++)? ???????System.out.println(a[i]);? }? }

2,希尔排序(最小增量排序)

(1)基本思想:算法先将要排序的一组数按某个增量d(n/2,n为要排序数的个数)分成若干组,每组中记录的下标相差d.对每组中全部元素进行直接插入排序,然后再用一个较小的增量(d/2)对它进行分组,在每组中再进行直接插入排序。当增量减到1时,进行直接插入排序后,排序完成。

(2)实例:


(3)用java实现

? public class shellSort {? public? shellSort(){? ????int a[]={1,54,6,3,78,34,12,45,56,100};? ????double d1=a.length;? ????int temp=0;? ????while(true){? ????????d1= Math.ceil(d1/2);? ????????int d=(int) d1;? ????????for(int x=0;x<d;x++){? ????????????for(int i=x+d;i<a.length;i+=d){? ????????????????int j=i-d;? ????????????????temp=a[i];? ????????????????for(;j>=0&&temp<a[j];j-=d){? ????????????????a[j+d]=a[j];? ????????????????}? ????????????????a[j+d]=temp;? ????????????}? ????????}? ????????if(d==1)? ????????????break;? ????}? ????for(int i=0;i<a.length;i++)? ????????System.out.println(a[i]);? }? }

3.简单选择排序

(1)基本思想:在要排序的一组数中,选出最小的一个数与第一个位置的数交换;

然后在剩下的数当中再找最小的与第二个位置的数交换,如此循环到倒数第二个数和最后一个数比较为止。

(2)实例:

(3)用java实现

? public class selectSort {? ????public selectSort(){? ????????int a[]={1,54,6,3,78,34,12,45};? ????????int position=0;? ????????for(int i=0;i<a.length;i++){? ? ????????????int j=i+1;? ????????????position=i;? ????????????int temp=a[i];? ????????????for(;j<a.length;j++){? ????????????if(a[j]<temp){? ????????????????temp=a[j];? ????????????????position=j;? ????????????}? ????????????}? ????????????a[position]=a[i];? ????????????a[i]=temp;? ????????}? ????????for(int i=0;i<a.length;i++)? ????????????System.out.println(a[i]);? ????}? }

4,堆排序

(1)基本思想:堆排序是一种树形选择排序,是对直接选择排序的有效改进。

堆的定义如下:具有n个元素的序列(h1,h2,…,hn),当且仅当满足(hi>=h2i,hi>=2i+1)或(hi<=h2i,hi<=2i+1) (i=1,2,…,n/2)时称之为堆。在这里只讨论满足前者条件的堆。由堆的定义可以看出,堆顶元素(即第一个元素)必为最大项(大顶堆)。完全hashu.html" target="_blank">二叉树可以很直观地表示堆的结构。堆顶为根,其它为左子树、右子树。初始时把要排序的数的序列看作是一棵顺序存储的二叉树,调整它们的存储序,使之成为一个堆,这时堆的根节点的数最大。然后将根节点与堆的最后一个节点交换。然后对前面(n-1)个数重新调整使之成为堆。依此类推,直到只有两个节点的堆,并对它们作交换,最后得到有n个节点的有序序列。从算法描述来看,堆排序需要两个过程,一是建立堆,二是堆顶与堆的最后一个元素交换位置。所以堆排序有两个函数组成。一是建堆的渗透函数,二是反复调用渗透函数实现排序的函数。

(2)实例:

初始序列:46,79,56,38,40,84

建堆:

交换,从堆中踢出最大数

依次类推:最后堆中剩余的最后两个结点交换,踢出一个,排序完成。

(3)用java实现

? import java.util.Arrays;? ? public class HeapSort {? ?????int a[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51};? ????public? HeapSort(){? ????????heapSort(a);? ????}? ????public? void heapSort(int[] a){? ????????System.out.println("开始排序");? ????????int arrayLength=a.length;? ????????//循环建堆? ????????for(int i=0;i<arrayLength-1;i++){? ????????????//建堆? ? ??????buildMaxHeap(a,arrayLength-1-i);? ????????????//交换堆顶和最后一个元素? ????????????swap(a,0,arrayLength-1-i);? ????????????System.out.println(Arrays.toString(a));? ????????}? ????}? ? ????private? void swap(int[] data, int i, int j) {? ????????// TODO Auto-generated method stub? ????????int tmp=data[i];? ????????data[i]=data[j];? ????????data[j]=tmp;? ????}? ????//对data数组从0到lastIndex建大顶堆? ????private void buildMaxHeap(int[] data, int lastIndex) {? ????????// TODO Auto-generated method stub? ????????//从lastIndex处节点(最后一个节点)的父节点开始? ????????for(int i=(lastIndex-1)/2;i>=0;i--){? ????????????//k保存正在判断的节点? ????????????int k=i;? ????????????//如果当前k节点的子节点存在? ????????????while(k*2+1<=lastIndex){? ????????????????//k节点的左子节点的索引? ????????????????int biggerIndex=2*k+1;? ????????????????//如果biggerIndex小于lastIndex,即biggerIndex+1代表的k节点的右子节点存在? ????????????????if(biggerIndex<lastIndex){? ????????????????????//若果右子节点的值较大? ????????????????????if(data[biggerIndex]<data[biggerIndex+1]){? ????????????????????????//biggerIndex总是记录较大子节点的索引? ????????????????????????biggerIndex++;? ????????????????????}? ????????????????}? ????????????????//如果k节点的值小于其较大的子节点的值? ????????????????if(data[k]<data[biggerIndex]){? ????????????????????//交换他们? ????????????????????swap(data,k,biggerIndex);? ????????????????????//将biggerIndex赋予k,开始while循环的下一次循环,重新保证k节点的值大于其左右子节点的值? ????????????????????k=biggerIndex;? ????????????????}else{? ????????????????????break;? ????????????????}? ????????????} ????????} ????} }

5.冒泡排序

(1)基本思想:在要排序的一组数中,对当前还未排好序的范围内的全部数,自上而下对相邻的两个数依次进行比较和调整,让较大的数往下沉,较小的往上冒。即:每当两相邻的数比较后发现它们的排序与排序要求相反时,就将它们互换。

(2)实例:

(3)用java实现

? public class bubbleSort {? public? bubbleSort(){? ?????int a[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51};? ????int temp=0;? ????for(int i=0;i<a.length-1;i++){? ????????for(int j=0;j<a.length-1-i;j++){? ????????if(a[j]>a[j+1]){? ????????????temp=a[j];? ????????????a[j]=a[j+1];? ????????????a[j+1]=temp;? ????????}? ????????}? ????}? ????for(int i=0;i<a.length;i++)? ????System.out.println(a[i]);???? }? }

6.快速排序

(1)基本思想:选择一个基准元素,通常选择第一个元素或者最后一个元素,通过一趟扫描,将待排序列分成两部分,一部分比基准元素小,一部分大于等于基准元素,此时基准元素在其排好序后的正确位置,然后再用同样的方法递归地排序划分的两部分。

(2)实例:

(3)用java实现

? public class quickSort {? ??int a[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51};? public? quickSort(){? ????quick(a);? ????for(int i=0;i<a.length;i++)? ????????System.out.println(a[i]);? }? public int getMiddle(int[] list, int low, int high) {???? ????????????int tmp = list[low];??? //数组的第一个作为中轴???? ????????????while (low < high) {???? ????????????????while (low < high && list[high] >= tmp) {???? ? ??????high--;???? ????????????????}???? ????????????????list[low] = list[high];?? //比中轴小的记录移到低端???? ????????????????while (low < high && list[low] <= tmp) {???? ????????????????????low++;???? ????????????????}???? ????????????????list[high] = list[low];?? //比中轴大的记录移到高端???? ????????????}???? ???????????list[low] = tmp;????????????? //中轴记录到尾???? ????????????return low;?????????????????? //返回中轴的位置???? ????????}??? public void _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);??????? //对低字表进行递归排序???? ???????????????_quickSort(list, middle + 1, high);?????? //对高字表进行递归排序???? ????????????}???? ????????}?? public void quick(int[] a2) {???? ????????????if (a2.length > 0) {??? //查看数组是否为空???? ????????????????_quickSort(a2, 0, a2.length - 1);???? ????????}???? ???????}?? }

7、归并排序

(1)基本排序:归并(Merge)排序法是将两个(或两个以上)有序表合并成一个新的有序表,即把待排序序列分为若干个子序列,每个子序列是有序的。然后再把有序子序列合并为整体有序序列。

(2)实例:

(3)用java实现

? import java.util.Arrays;? ? public class mergingSort {? int a[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51};? public? mergingSort(){? ????sort(a,0,a.length-1);? ????for(int i=0;i<a.length;i++)? ????????System.out.println(a[i]);? }? public void sort(int[] data, int left, int right) {? ????// TODO Auto-generated method stub? ????if(left<right){? ????????//找出中间索引? ????????int center=(left+right)/2;? ????????//对左边数组进行递归? ????????sort(data,left,center);? ????????//对右边数组进行递归? ????????sort(data,center+1,right);? ????????//合并? ????????merge(data,left,center,right);? ? ????}? }? public void merge(int[] data, int left, int center, int right) {? ????// TODO Auto-generated method stub? ????int [] tmpArr=new int[data.length];? ????int mid=center+1;? ????//third记录中间数组的索引? ????int third=left;? ????int tmp=left;? ????while(left<=center&&mid<=right){? ? ???//从两个数组中取出最小的放入中间数组? ????????if(data[left]<=data[mid]){? ????????????tmpArr[third++]=data[left++];? ????????}else{? ????????????tmpArr[third++]=data[mid++];? ????????}? ????}? ????//剩余部分依次放入中间数组? ????while(mid<=right){? ????????tmpArr[third++]=data[mid++];? ????}? ????while(left<=center){? ????????tmpArr[third++]=data[left++];? ????}? ????//将中间数组中的内容复制回原数组? ????while(tmp<=right){? ????????data[tmp]=tmpArr[tmp++];? ????}? ????System.out.println(Arrays.toString(data));? }? ? }

8、基数排序

(1)基本思想:将所有待比较数值(正整数)统一为同样的数位长度,数位较短的数前面补零。然后,从最低位开始,依次进行一次排序。这样从最低位排序一直到最高位排序完成以后,数列就变成一个有序序列。

(2)实例:

(3)用java实现

? import java.util.ArrayList;? import java.util.List;? ? public class radixSort {? ????int a[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,101,56,17,18,23,34,15,35,25,53,51};? public radixSort(){? ????sort(a);? ????for(int i=0;i<a.length;i++)? ????????System.out.println(a[i]);? }? public? void sort(int[] array){???? ? ????????????//首先确定排序的趟数;???? ????????int max=array[0];???? ????????for(int i=1;i<array.length;i++){???? ???????????????if(array[i]>max){???? ???????????????max=array[i];???? ???????????????}???? ????????????}???? ? ????int time=0;???? ???????????//判断位数;???? ????????????while(max>0){???? ???????????????max/=10;???? ????????????????time++;???? ????????????}???? ? ????????//建立10个队列;???? ????????????List<ArrayList> queue=new ArrayList<ArrayList>();???? ????????????for(int i=0;i<10;i++){???? ????????????????ArrayList<Integer> queue1=new ArrayList<Integer>();?? ????????????????queue.add(queue1);???? ????????}???? ? ????????????//进行time次分配和收集;???? ????????????for(int i=0;i<time;i++){???? ? ????????????????//分配数组元素;???? ???????????????for(int j=0;j<array.length;j++){???? ????????????????????//得到数字的第time+1位数;?? ???????????????????int x=array[j]%(int)Math.pow(10, i+1)/(int)Math.pow(10, i);? ???????????????????ArrayList<Integer> queue2=queue.get(x);? ???????????????????queue2.add(array[j]);? ???????????????????queue.set(x, queue2);? ????????????}???? ????????????????int count=0;//元素计数器;???? ????????????//收集队列元素;???? ????????????????for(int k=0;k<10;k++){?? ????????????????while(queue.get(k).size()>0){? ????????????????????ArrayList<Integer> queue3=queue.get(k);? ????????????????????????array[count]=queue3.get(0);???? ????????????????????????queue3.remove(0);? ????????????????????count++;? ??????????????}???? ????????????}???? ??????????}???? ? ???}??? ? } ? ?SpringMVC+mybatis HTML5 全新高大尚后台框架_集成代码生成器
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