java快速排序簡(jiǎn)單代碼

.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《數(shù)據(jù)結(jié)構(gòu)與算法》中最基本的算法之一。排序算法可以分為內(nèi)部排序和外部排序，內(nèi)部排序是數(shù)據(jù)記錄在內(nèi)存中進(jìn)行排序，而外部排序是因排序的數(shù)據(jù)很大，一次不能容納全部的排序記錄，在排序過(guò)程中需要訪問(wèn)外存。常見(jiàn)的內(nèi)部排序算法有：插入排序、希爾排序、選擇排序、冒泡排序、歸并排序、快速排序、堆排序、基數(shù)排序等。以下是快速排序算法：

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快速排序是由東尼·霍爾所發(fā)展的一種排序算法。在平均狀況下，排序 n 個(gè)項(xiàng)目要 Ο(nlogn) 次比較。在最壞狀況下則需要 Ο(n2) 次比較，但這種狀況并不常見(jiàn)。事實(shí)上，快速排序通常明顯比其他 Ο(nlogn) 算法更快，因?yàn)樗膬?nèi)部循環(huán)（inner loop）可以在大部分的架構(gòu)上很有效率地被實(shí)現(xiàn)出來(lái)。

快速排序使用分治法（Divide and conquer）策略來(lái)把一個(gè)串行（list）分為兩個(gè)子串行（sub-lists）。

快速排序又是一種分而治之思想在排序算法上的典型應(yīng)用。本質(zhì)上來(lái)看，快速排序應(yīng)該算是在冒泡排序基礎(chǔ)上的遞歸分治法。

快速排序的名字起的是簡(jiǎn)單粗暴，因?yàn)橐宦?tīng)到這個(gè)名字你就知道它存在的意義，就是快，而且效率高！它是處理大數(shù)據(jù)最快的排序算法之一了。雖然 Worst Case 的時(shí)間復(fù)雜度達(dá)到了 O(n?)，但是人家就是優(yōu)秀，在大多數(shù)情況下都比平均時(shí)間復(fù)雜度為 O(n logn) 的排序算法表現(xiàn)要更好，可是這是為什么呢，我也不知道。好在我的強(qiáng)迫癥又犯了，查了 N 多資料終于在《算法藝術(shù)與信息學(xué)競(jìng)賽》上找到了滿意的答案：

快速排序的最壞運(yùn)行情況是 O(n?)，比如說(shuō)順序數(shù)列的快排。但它的平攤期望時(shí)間是 O(nlogn)，且 O(nlogn) 記號(hào)中隱含的常數(shù)因子很小，比復(fù)雜度穩(wěn)定等于 O(nlogn) 的歸并排序要小很多。所以，對(duì)絕大多數(shù)順序性較弱的隨機(jī)數(shù)列而言，快速排序總是優(yōu)于歸并排序。

1. 算法步驟

從數(shù)列中挑出一個(gè)元素，稱為 "基準(zhǔn)"（pivot）;

重新排序數(shù)列，所有元素比基準(zhǔn)值小的擺放在基準(zhǔn)前面，所有元素比基準(zhǔn)值大的擺在基準(zhǔn)的后面（相同的數(shù)可以到任一邊）。在這個(gè)分區(qū)退出之后，該基準(zhǔn)就處于數(shù)列的中間位置。這個(gè)稱為分區(qū)（partition）操作；

遞歸地（recursive）把小于基準(zhǔn)值元素的子數(shù)列和大于基準(zhǔn)值元素的子數(shù)列排序；

2. 動(dòng)圖演示

代碼實(shí)現(xiàn) JavaScript 實(shí)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

求java快速排序的正確代碼

一趟快速怕序的具體做法是：附設(shè)兩個(gè)指針low和high,他們的初值分別為low和high,設(shè)樞軸記錄的關(guān)鍵字為privotkey,則首先從high所指位置向前搜索找到第一個(gè)關(guān)鍵字小于pivotkey的記錄和樞軸記錄互相交換,然后從low所指向的位置起向后搜索,找到第一個(gè)關(guān)鍵字大于privotkey的記錄和樞軸記錄互相交換，重復(fù)這兩步直至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){

/**

* 選擇 low位置 作為曲軸(支點(diǎn))

*/

int pivot=array[low];

int temp=0;

/**

* 如果 low

*/

while(low

/**

* 先從 high端 開(kāi)始判斷

*/

while(low=pivot) high--;

/**

* 進(jìn)行 置換操作

*/

if(low

array[low]=array[high];

low++;

}

/**

* 從 low 端判斷

*/

while(low

/**

* 進(jìn)行 置換操作

*/

if(low

array[high]=array[low];

high--;

}

}

array[low]=pivot;

return low;

}

}

java中排序算法代碼

package temp;

import sun.misc.Sort;

/**

* @author zengjl

* @version 1.0

* @since 2007-08-22

* @Des java幾種基本排序方法

*/

/**

* SortUtil:排序方法

* 關(guān)于對(duì)排序方法的選擇：這告訴我們，什么時(shí)候用什么排序最好。當(dāng)人們渴望先知道排在前面的是誰(shuí)時(shí)，

* 我們用選擇排序；當(dāng)我們不斷拿到新的數(shù)并想保持已有的數(shù)始終有序時(shí)，我們用插入排序；當(dāng)給出的數(shù)

* 列已經(jīng)比較有序，只需要小幅度的調(diào)整一下時(shí)，我們用冒泡排序。

*/

public class SortUtil extends Sort {

/**

* 插入排序法

* @param data

* @Des 插入排序(Insertion Sort)是，每次從數(shù)列中取一個(gè)還沒(méi)有取出過(guò)的數(shù)，并按照大小關(guān)系插入到已經(jīng)取出的數(shù)中使得已經(jīng)取出的數(shù)仍然有序。

*/

public int[] insertSort(int[] data) {

1/11頁(yè)

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)分為若干趟進(jìn)行，每一趟排序從前往后比較每?jī)蓚€(gè)相鄰的元素的大小（因此一趟排序要比較n-1對(duì)位置相鄰的數(shù)）并在

* 每次發(fā)現(xiàn)前面的那個(gè)數(shù)比緊接它后的數(shù)大時(shí)交換位置；進(jìn)行足夠多趟直到某一趟跑完后發(fā)現(xiàn)這一趟沒(méi)有進(jìn)行任何交換操作（最壞情況下要跑n-1趟，

* 這種情況在最小的數(shù)位于給定數(shù)列的最后面時(shí)發(fā)生）。事實(shí)上，在第一趟冒泡結(jié)束后，最后面那個(gè)數(shù)肯定是最大的了，于是第二次只需要對(duì)前面n-1

* 個(gè)數(shù)排序，這又將把這n-1個(gè)數(shù)中最小的數(shù)放到整個(gè)數(shù)列的倒數(shù)第二個(gè)位置。這樣下去，冒泡排序第i趟結(jié)束后后面i個(gè)數(shù)都已經(jīng)到位了，第i+1趟實(shí)

* 際上只考慮前n-i個(gè)數(shù)（需要的比較次數(shù)比前面所說(shuō)的n-1要小）。這相當(dāng)于用數(shù)學(xué)歸納法證明了冒泡排序的正確性

直接選擇排序Java實(shí)現(xiàn)

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:

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