java实现常见的排序（冒泡、插入、选择、快排）

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最近正在找实习发现大公司第一轮的笔试都是没有重点考的很广也很基础其中数据结构的比重很大我顺便练了练把这些代码贴出来放在这里以后也能用的上

ps：每个代码都写成一个class然后里面也有一个比较排序速度的main方法，有一个直观的排序效率展示

1 冒泡排序

package com.sort.implement;//冒泡排序public class BubbleSort {public BubbleSort(int[] a) {for(int i = 0; i< a.length-1;i++){for(int j = 0; j<a.length-i-1;j++){if(a[j]>a[j+1]){int temp = a[j];a[j]=a[j+1];a[j+1]=temp;}}}}public static void main(String[] args) {int []a = new int[]{5,4,3,2,1};//int []b = new int[]{26,53,48,11,13,48,32,15};double timer = System.nanoTime();BubbleSort s= new BubbleSort(a);//计算用时 ,下同System.out.println(System.nanoTime()-timer);for(int i = 0 ; i < a.length;i++){System.out.print(a[i]+" ");}}}

2 插入排序

package com.sort.implement;//插入排序public class InsertSort {public InsertSort(int []a){for(int i = 1;i < a.length;i++){int temp = a[i];int j = i-1; while(j>=0&&a[j]>temp){a[j+1] = a[j];j--;}a[j+1] = temp;}}public static void main(String[] args) {int []a = new int[]{5,4,3,2,1};double timer = System.nanoTime();InsertSort i1 = new InsertSort(a);System.out.println(System.nanoTime()-timer);for(int i = 0 ; i < a.length;i++){System.out.print(a[i]+" ");}}}

3 选择排序

package com.sort.implement;//选择排序public class SelectSort {private  SelectSort(int [] a) {// TODO Auto-generated method stubint len = a.length;for(int i = 0 ; i < len-1 ; i++){for(int j = i+1 ; j<len ;j++){if(a[i]>a[j]){int temp= a[i];a[i]=a[j];a[j]=temp;}}}}public static void main(String[] args) {int a[] = new int[]{5,4,3,2,1};double timer = System.nanoTime();SelectSort s = new SelectSort(a);System.out.println(System.nanoTime()-timer);for(int i = 0 ; i < a.length;i++){System.out.print(a[i]+" ");}}}

4 快速排序

package com.sort.implement;//快速排序public class QuickSort {public QuickSort(int []a,int low,int high ){int i=low;int j=high;int keyValue=a[i];while(i<j){int temp=0;while(i<j&&a[j]>=keyValue){j=j-1;}temp=a[j];a[j]=a[i];a[i]=temp;while(i<j&&a[i]<=keyValue){i=i+1;}temp=a[j];a[j]=a[i];a[i]=temp;}a[i]=keyValue;if(low<i-1){new QuickSort(a,low,i-1);}if(high>i+1){new QuickSort(a,i+1,high);}}public static void main(String[] args) {int a[] = new int[]{5,4,3,2,1};double timer = System.nanoTime();System.out.println(System.nanoTime()-timer);QuickSort i1 = new QuickSort(a,0,a.length-1);for(int i = 0 ; i < a.length;i++){System.out.print(a[i]+" ");}}}