.example-btn{color:#fff;background-color:#5cb85c;border-color:#4cae4c}.example-btn:hover{color:#fff;background-color:#47a447;border-color:#398439}.example-btn:active{background-image:none}div.example{width:98%;color:#000;background-color:#f6f4f0;background-color:#d0e69c;background-color:#dcecb5;background-color:#e5eecc;margin:0 0 5px 0;padding:5px;border:1px solid #d4d4d4;background-image:-webkit-linear-gradient(#fff,#e5eecc 100px);background-image:linear-gradient(#fff,#e5eecc 100px)}div.example_code{line-height:1.4em;width:98%;background-color:#fff;padding:5px;border:1px solid #d4d4d4;font-size:110%;font-family:Menlo,Monaco,Consolas,"Andale Mono","lucida console","Courier New",monospace;word-break:break-all;word-wrap:break-word}div.example_result{background-color:#fff;padding:4px;border:1px solid #d4d4d4;width:98%}div.code{width:98%;border:1px solid #d4d4d4;background-color:#f6f4f0;color:#444;padding:5px;margin:0}div.code div{font-size:110%}div.code div,div.code p,div.example_code p{font-family:"courier new"}pre{margin:15px auto;font:12px/20px Menlo,Monaco,Consolas,"Andale Mono","lucida console","Courier New",monospace;white-space:pre-wrap;word-break:break-all;word-wrap:break-word;border:1px solid #ddd;border-left-width:4px;padding:10px 15px} 排序算法是《数据结构与算法》中最基本的算法之一。排序算法可以分为内部排序和外部排序，内部排序是数据记录在内存中进行排序，而外部排序是因排序的数据很大，一次不能容纳全部的排序记录，在排序过程中需要访问外存。常见的内部排序算法有：插入排序、希尔排序、选择排序、冒泡排序、归并排序、快速排序、堆排序、基数排序等。以下是快速排序算法：
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快速排序是由东尼·霍尔所发展的一种排序算法。在平均状况下，排序 n 个项目要 Ο(nlogn) 次比较。在最坏状况下则需要 Ο(n2) 次比较，但这种状况并不常见。事实上，快速排序通常明显比其他 Ο(nlogn) 算法更快，因为它的内部循环（inner loop）可以在大部分的架构上很有效率地被实现出来。
快速排序使用分治法（Divide and conquer）策略来把一个串行（list）分为两个子串行（sub-lists）。
快速排序又是一种分而治之思想在排序算法上的典型应用。本质上来看，快速排序应该算是在冒泡排序基础上的递归分治法。
快速排序的名字起的是简单粗暴，因为一听到这个名字你就知道它存在的意义，就是快，而且效率高！它是处理大数据最快的排序算法之一了。虽然 Worst Case 的时间复杂度达到了 O(n?)，但是人家就是优秀，在大多数情况下都比平均时间复杂度为 O(n logn) 的排序算法表现要更好，可是这是为什么呢，我也不知道。好在我的强迫症又犯了，查了 N 多资料终于在《算法艺术与信息学竞赛》上找到了满意的答案：
快速排序的最坏运行情况是 O(n?)，比如说顺序数列的快排。但它的平摊期望时间是 O(nlogn)，且 O(nlogn) 记号中隐含的常数因子很小，比复杂度稳定等于 O(nlogn) 的归并排序要小很多。所以，对绝大多数顺序性较弱的随机数列而言，快速排序总是优于归并排序。
1. 算法步骤
从数列中挑出一个元素，称为 "基准"（pivot）;
重新排序数列，所有元素比基准值小的摆放在基准前面，所有元素比基准值大的摆在基准的后面（相同的数可以到任一边）。在这个分区退出之后，该基准就处于数列的中间位置。这个称为分区（partition）操作；
递归地（recursive）把小于基准值元素的子数列和大于基准值元素的子数列排序；
2. 动图演示
代码实现 JavaScript 实例 function quickSort ( arr , left , right ) {
var len = arr. length ,
partitionIndex ,
left = typeof left != 'number' ? 0 : left ,
right = typeof right != 'number' ? len - 1 : right ;
if ( left
一趟快速怕序的具体做法是：附设两个指针low和high,他们的初值分别为low和high,设枢轴记录的关键字为privotkey,则首先从high所指位置向前搜索找到第一个关键字小于pivotkey的记录和枢轴记录互相交换,然后从low所指向的位置起向后搜索,找到第一个关键字大于privotkey的记录和枢轴记录互相交换，重复这两步直至low==high位置.
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class 快速排序_1 {
public static void main(String[] args) throws InterruptedException {
int test[] = {15,23,56,7,13,52,20,7};
new 快速排序_1().qSort(test, 0, test.length-1);
for(int k:test) System.out.println(k);
}
public void qSort(int []array,int low,int high){
if(low
int privot=partition(array,low,high);
qSort(array,low,privot-1);
qSort(array,privot+1,high);
}
}
public int partition(int [] array,int low,int high){
/**
* 选择 low位置 作为曲轴(支点)
*/
int pivot=array[low];
int temp=0;
/**
* 如果 low
*/
while(low
/**
* 先从 high端 开始判断
*/
while(low=pivot) high--;
/**
* 进行 置换操作
*/
if(low
array[low]=array[high];
low++;
}
/**
* 从 low 端判断
*/
while(low
/**
* 进行 置换操作
*/
if(low
array[high]=array[low];
high--;
}
}
array[low]=pivot;
return low;
}
}
package temp;
import sun.misc.Sort;
/**
* @author zengjl
* @version 1.0
* @since 2007-08-22
* @Des java几种基本排序方法
*/
/**
* SortUtil:排序方法
* 关于对排序方法的选择：这告诉我们，什么时候用什么排序最好。当人们渴望先知道排在前面的是谁时，
* 我们用选择排序；当我们不断拿到新的数并想保持已有的数始终有序时，我们用插入排序；当给出的数
* 列已经比较有序，只需要小幅度的调整一下时，我们用冒泡排序。
*/
public class SortUtil extends Sort {
/**
* 插入排序法
* @param data
* @Des 插入排序(Insertion Sort)是，每次从数列中取一个还没有取出过的数，并按照大小关系插入到已经取出的数中使得已经取出的数仍然有序。
*/
public int[] insertSort(int[] data) {
1/11页
int temp;
for (int i = 1; i data.length; i++) {
for (int j = i; (j 0) (data[j] data[j - 1]); j--) {
swap(data, j, j - 1);
}
}
return data;
}
/**
* 冒泡排序法
* @param data
* @return
* @Des 冒泡排序(Bubble Sort)分为若干趟进行，每一趟排序从前往后比较每两个相邻的元素的大小（因此一趟排序要比较n-1对位置相邻的数）并在
* 每次发现前面的那个数比紧接它后的数大时交换位置；进行足够多趟直到某一趟跑完后发现这一趟没有进行任何交换操作（最坏情况下要跑n-1趟，
* 这种情况在最小的数位于给定数列的最后面时发生）。事实上，在第一趟冒泡结束后，最后面那个数肯定是最大的了，于是第二次只需要对前面n-1
* 个数排序，这又将把这n-1个数中最小的数放到整个数列的倒数第二个位置。这样下去，冒泡排序第i趟结束后后面i个数都已经到位了，第i+1趟实
* 际上只考虑前n-i个数（需要的比较次数比前面所说的n-1要小）。这相当于用数学归纳法证明了冒泡排序的正确性
About this application:
This application implements Straight Selection Sort algorithm which is described like this:
If there are N numbers find the minimum and exchange it with the first number then N numbers remained Continue to find the minimum number in the remained N numbers and exchange it with the second number Repeat this until all the numbers are in order
Note: This is SWT application so you need eclipse swt win win x _ v b jar eclipse jface_ I jar mands_ I jar This is for Eclipse
Source Code:
package selection sort;
import java util ArrayList;
import eclipse swt SWT;
import eclipse swt events KeyAdapter;
import eclipse swt events KeyEvent;
import eclipse swt events ModifyEvent;
import eclipse swt events ModifyListener;
import eclipse swt events SelectionAdapter;
import eclipse swt events SelectionEvent;
import eclipse swt layout FormAttachment;
import eclipse swt layout FormData;
import eclipse swt layout FormLayout;
import eclipse swt widgets Button;
import eclipse swt widgets Display;
import eclipse swt widgets Group;
import eclipse swt widgets Label;
import eclipse swt widgets Shell;
import eclipse swt widgets Text;
/**
* This application implements Straight Selection Sort algorithm which means
* get the minimum number from the numbers and exchange it with the first
* number then doing this for other numbers except the first number Repeat
* this until all numbers are in order If you have any suggestion or problem
* please e mail to
*
* @author vivien Data:
*/
public class StraightSelectionSort {
/** The string containing the number wait for sorted */
public String numString = new String();
public Text numText;
public Text resText;
public Button btSort;
public Label errorLabel;
/** The flag to indicate if there is any error for inputed numbers */
public boolean hasError = false;
/** The arrayList containing the double numbers wait for sorted */
public ArrayListDouble numList = new ArrayListDouble();
public static void main(String[] args) {
StraightSelectionSort selectionSort = new StraightSelectionSort();
selectionSort createControl();
}
/**
* Create the control for the interface
*/
public void createControl() {
Display display = new Display();
Shell shell = new Shell(display);
shell setBounds( );
// Set Title
shell setText( Straight selection sort );
FormLayout layout = new FormLayout();
shell setLayout(layout);
FormData fd = new FormData();
// The Start Sort button
btSort = new Button(shell SWT NONE | SWT CENTER);
btSort setText( Start Sort );
fd = new FormData();
fd height = ;
fd top = new FormAttachment( );
fd left = new FormAttachment( );
btSort setLayoutData(fd);
// The Input numbers group
Group numGroup = new Group(shell SWT NONE);
numGroup setText( Input numbers: );
numGroup setLayout(layout);
fd = new FormData();
fd top = new FormAttachment( );
fd left = new FormAttachment( );
fd right = new FormAttachment( );
fd bottom = new FormAttachment(btSort );
numGroup setLayoutData(fd);
// Label for input numbers
Label numLabel = new Label(numGroup SWT WRAP);
numLabel
setText( Please input the numbers you want to sort: (Note: Numbers need to be seperated by space) );
fd = new FormData();
fd top = new FormAttachment( );
fd left = new FormAttachment( );
fd right = new FormAttachment( );
numLabel setLayoutData(fd);
// Text for input numbers
numText = new Text(numGroup SWT BORDER | SWT MULTI | SWT V_SCROLL
| SWT WRAP);
numText setToolTipText( Numbers need to be seperated by space );
fd = new FormData();
fd top = new FormAttachment(numLabel );
fd left = new FormAttachment( );
fd right = new FormAttachment( );
fd bottom = new FormAttachment( );
numText setLayoutData(fd);
// The results group
Group resGroup = new Group(shell SWT NONE);
resGroup setText( The results: );
resGroup setLayout(layout);
fd = new FormData();
fd top = new FormAttachment(btSort );
fd left = new FormAttachment( );
fd right = new FormAttachment( );
fd bottom = new FormAttachment( );
resGroup setLayoutData(fd);
// Label for results
Label resLabel = new Label(resGroup SWT WRAP);
resLabel
setText( The results after sorted are: (Note: Results are seperated by space) );
fd = new FormData();
fd top = new FormAttachment( );
fd left = new FormAttachment( );
fd right = new FormAttachment( );
resLabel setLayoutData(fd);
// Text for results
resText = new Text(resGroup SWT BORDER | SWT MULTI | SWT V_SCROLL
| SWT WRAP);
resText setToolTipText( Results are seperated by space );
resText setEditable(false);
fd = new FormData();
fd top = new FormAttachment(resLabel );
fd left = new FormAttachment( );
fd right = new FormAttachment( );
fd bottom = new FormAttachment( );
resText setLayoutData(fd);
// Label for showing error message
errorLabel = new Label(shell SWT NONE);
fd = new FormData();
fd top = new FormAttachment( );
fd left = new FormAttachment( );
fd right = new FormAttachment( );
fd bottom = new FormAttachment( );
errorLabel setLayoutData(fd);
errorLabel setForeground(display getSystemColor(SWT COLOR_RED));
// Listen to the numText change
numText addModifyListener(new ModifyListener() {
@Override
public void modifyText(ModifyEvent e) {
numString = numText getText() trim();
hasError = false;
}
});
// If press Return focus go to Start Sort button and start sort
numText addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
if (e keyCode == \r ) {
e doit = false;
btSort setFocus();
startSort();
}
}
});
// Listen to the button selection
btSort addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
startSort();
}
});
shell open();
while (!shell isDisposed()) {
if (!display readAndDispatch())
display sleep();
}
display dispose();
}
/**
* Get double values from string
*/
public void getDoubleFromString() {
int index = ;
// Split string using space
String[] splitedNumbers = numString split( );
if (numList size() != )
// Clear the arrayList for last used
numList clear();
for (int i = ; i splitedNumbers length; i++) {
if (splitedNumbers[i] trim() length() != ) {
try {
numList add(index++ Double valueOf(splitedNumbers[i]));
} catch (NumberFormatException e) {
setErrorMessage( Please input the correct numbers );
hasError = true;
break;
}
}
}
}
/**
* Start sort the string containing numbers waited for sort
*/
public void startSort() {
if (numString != null)
if (numString trim() length() != ) {
getDoubleFromString();
startStraightSelectionSort();
setResults();
} else {
setErrorMessage( Please input numbers );
hasError = true;
}
}
/**
* Set the results to the results group
*/
public void setResults() {
if (!hasError) {
String resString = new String();
for (int i = ; i numList size(); i++)
if (i != numList size() )
resString = resString + numList get(i) + ;
else
// If be the last string
resString = resString + numList get(i);
resText setText(resString);
// Clear errorLabel
errorLabel setText( );
}
}
/**
* Sort the numbers using Straight selection Sort algorithm
*/
public void startStraightSelectionSort() {
int minPosition = ;
for (int j = ; j numList size() ; j++) {
minPosition = j;
for (int i = j + ; i numList size(); i++) {
if (numList get(i) numList get(minPosition)) {
minPosition = i;
}
}
if (minPosition != j) {
// Exchange the minimum with the first number of the numbers
// waited for sort
double temp = numList get(j);
numList set(j numList get(minPosition));
numList set(minPosition temp);
}
}
}
/**
* Set the error message on the error Label
*
* @param errorString
* The string used for set on the errorLabel
*/
public void setErrorMessage(String errorString) {
errorLabel setText(errorString);
// Clear the text of results
resText setText( );
hasError = true;
}
}
Black box Test Case:
) All numbers are zero: