排序算法

 

1.bubbleSort

import java.util.Scanner;public class BubleSort {/** * @param args   2011.10.05 */public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int num;int[] nums = new int[100];int i=0;while (true) {num=scanner.nextInt();if (num==-1)break;nums[i++] = num;}bubblesort(nums,i);for(int j=0;j<i;j++){System.out.print(nums[j]+" ");}System.out.println();}static void bubblesort(int[] nums,int n){for( int i=0;i<n-1;i++){boolean changed=false;for(int j=n-1;j>=i+1;j--){if(nums[j-1]>nums[j]){nums[j-1]=nums[j-1]+nums[j];nums[j]=nums[j-1]-nums[j];nums[j-1]=nums[j-1]-nums[j];//int tmp=nums[j-1];//nums[j-1]=nums[j];//nums[j]=tmp;changed=true;}}if(!changed) break;}}}

2.quicksort

#include <stdio.h>#include <stdlib.h>void swap(int *a,int *b)/*交换*/{int temp=*a;*a=*b;*b=temp;}int partition(int data[],int l, int h)  /*i的作用是指向可被交换的位置，j指向待判断的位置,返回中值位置*/{int i=l-1;int j;int pivot=data[h];for(j=1;j<h;j++){if(data[j]<pivot){i++;swap(&data[i],&data[j]);}}swap(&data[i+1],&data[h]);return i+1;}void quicksort(int data[],int l, int h){if(l<h){int k=partition(data,l,h);quicksort(data,l,k-1);quicksort(data,k+1,h);}}int main(){int data[] ={5,6,3,2,1};quicksort(data,0,4);for(int t=0;t<5;t++){cout<<data[t]<<" "<<endl;}return 0;}1,3,4,5,2

快排有一个地方值得注意：partition的时候，两个标志位既可以同时先后从左往右，也可以一左一右同时进行。

int partition2(int data[],int l,int h){int i=l;int j=h;int pivot=data[i];for(i<j){while(data[j]>=pivot && i<j)j--;data[i]=data[j];while(data[i]<=pivot && i<j)i++;data[j]=data[i];}data[i]=pivot;return i;}

代码来自july

quicksort java version

public static <T extends Comparable<? super T>> void quickSort(T[]a, int low, int high){if(low+CUTOFF>high)  //子列较小时采用插入排序insertionSort(a,low,high);else{int middle=(low+high)/2;if(a[middle].compareTo(a[low])<0)swapReference(a,low,middle);if(a[high].compareTo(a[low])<0)swapReference(a,low,middle);if(a[high].compareTo(a[middle])<0)swapReference(a,middle,high);swapReference(a,middle,high-1);        //将middle位置的元素放在high-1位置T pivot = a[high-1];int i,j;for(i=low,j=high;;){while(a[++i].compareTo(pivot)<0);while(pivot.compareTo(a[--j])<0);if(i>=j)break;swapReference(a,i,j);}swapReference(a,i,high-1);quickSort(a, low, i-1);quickSort(a, i+1, high);}}

自己写的quicksort

public class QuickSort {/** * @param args */public static void main(String[] args) {int[] nums = { 2, 55, 33, 11, 9 };quicksort(nums, 0, nums.length - 1);for (int i = 0; i < nums.length; i++) {System.out.print(nums[i] + " ");}System.out.println();}static void quicksort(int nums[], int low, int high) {               //这里体现的是divide and conquer的思想。if (low < high) {   int pivotpos = partition(nums, low, high);quicksort(nums, low, pivotpos - 1);quicksort(nums, pivotpos + 1, high);}}static int partition(int[] nums, int low, int high) {int pivotpos=low;                                           //quick sort的速度取决于输入，此外很到程度上跟pivot的选择有关！int pivot = nums[low];for(int i=low+1;i<=high;i++){                               //这个循环里面的内容是比较难以理解的。脑子里多过即便就好了if(nums[i]<pivot){pivotpos++;if(i!=pivotpos) {int tmp=nums[i];nums[i]=nums[pivotpos];nums[pivotpos]=tmp;}}}nums[low]=nums[pivotpos];nums[pivotpos]=pivot;return pivotpos;}}

3.ShellSort

import java.util.Scanner;public class ShellSort {/** * @param args  2011.10.05  值得注意的是：直接插入排序其实就是gap=1的时候的 * 希尔排序情形。熟悉了直接插入排序那么希尔排序也就很容易写出来了。 */public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int n = 0; // 待排序数组长度int num;int[] nums = new int[100];while (true) {num = scanner.nextInt();if (num == -1)break;nums[n++] = num;}shellsort(nums, n);for (int i = 0; i < n; i++) {System.out.print(nums[i] + " ");}System.out.println();}static void shellsort(int[] nums, int n) {int gap = n;do {gap = gap / 3 + 1;for (int i = gap; i < n; i++) {if (nums[i - gap] > nums[i]) {int tmp = nums[i];int j = i - gap;do {nums[j + gap] = nums[j];j = j - gap;} while (j >= 0 && nums[j] > tmp);nums[j + gap] = tmp;}}} while (gap > 1);}}

4.insertion sort

import java.util.Scanner;public class InsertSort {/** * @param args */public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int num;int[] nums = new int[100];int n=0;   //数组长度while(true){num=scanner.nextInt();if(num==-1) break;nums[n++]=num;}insertsort(nums, n);for(int i=0;i<n;i++){System.out.print(nums[i]+" ");}System.out.println();}static void insertsort(int[] nums, int n){for( int i=1;i<n;i++){if(nums[i-1]>nums[i]){int tmp=nums[i];int j=i-1;do {nums[j+1]=nums[j];j--;} while (j>=0 && nums[j]>tmp);nums[j+1]=tmp;}}}}

5.binary insertion sort

import java.util.Scanner;public class BinaryInsertSort {/** * @param args */public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int n=0;             //待排序数组长度int num;int[] nums = new int[100];while(true){num=scanner.nextInt();if(num==-1) break;nums[n++]=num;}binaryinsertsort(nums, n);for(int i=0;i<n;i++){System.out.print(nums[i]+" ");}System.out.println();}static void binaryinsertsort(int nums[], int n){for(int i=1;i<n;i++){int temp=nums[i];int low=0;int high=i-1;while(low<=high){            //这里的等号很关键int mid=(low+high)/2;if(nums[mid]<nums[i]){low=mid+1;}else{high=mid-1;}}for(int j=i-1;j>=low;j--){nums[j+1]=nums[j];}nums[low]=temp;}}}

6.计数排序

import java.util.Scanner;import javax.security.auth.kerberos.KerberosKey;public class CountingSort {/** * @param args */public static void main(String[] args) {Scanner scanner = new Scanner(System.in);System.out.print("0~n?n=");int n=scanner.nextInt();System.out.print("length of the unsorted array?:");int lenthA=scanner.nextInt();System.out.println("please enter the unsorted array(end with -1):");int[] A = new int[lenthA];int [] B = new int[lenthA];int i=0;while(true){int k=scanner.nextInt();if(k==-1) break;A[i++]=k;}int [] C = new int[n+1];countingsort(A, B, C);for(int j=0;j<A.length;j++){System.out.print(" "+B[j]);}}static void countingsort(int[] A,int[] B,int[] C){for(int i=0;i<C.length;i++){C[i]=0;}for(int j=0;j<A.length;j++){C[A[j]]=C[A[j]]+1;}for(int i=1;i<C.length;i++){C[i]=C[i]+C[i-1];}for(int j=A.length-1;j>=0;j--){B[C[A[j]]-1]=A[j];C[A[j]]=C[A[j]]-1;}}}

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