.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，在排序過程中需要訪問外存。常見的內(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。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。
快速排序使用分治法（Divide and conquer）策略來把一個(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單粗暴，因?yàn)橐宦牭竭@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
你是想要幫你完善一下，然后可以運(yùn)行是吧？？
代碼如下：
public?class?Test?{
public?void?sortFistname(String[]?args)?{
String?temp;
System.out.println("按首字母排序");
for?(int?i?=?0;?i??args.length?-?1;?i++)?{
int?maxIndex?=?i;
String?max?=?args[i];
for?(int?j?=?i?+?1;?j??args.length;?j++)?{
int?a?=?max.compareTo(args[j]);
if?(a??0)?{
maxIndex?=?j;
}
}
if?(maxIndex?!=?i)?{
temp?=?args[i];
args[i]?=?args[maxIndex];
args[maxIndex]?=?temp;
}
}
for(int?i=0;iargs.length;i++)?{
System.out.println(args[i]);
}
}
public?Test()?{
String[]?args?=?{"abc","afew","ebwe","gverg","nrgerg"};
sortFistname(args);
}
public?static?void?main(String[]?args)?{
new?Test();
}
}
冒泡排序是比較經(jīng)典的排序算法。代碼如下：
for(int i=1;iarr.length;i++){
for(int j=1;jarr.length-i;j++){
//交換位置
} ? ?
拓展資料：
原理：比較兩個(gè)相鄰的元素，將值大的元素交換至右端。
思路：依次比較相鄰的兩個(gè)數(shù)，將小數(shù)放在前面，大數(shù)放在后面。即在第一趟：首先比較第1個(gè)和第2個(gè)數(shù)，將小數(shù)放前，大數(shù)放后。然后比較第2個(gè)數(shù)和第3個(gè)數(shù)，將小數(shù)放前，大數(shù)放后，如此繼續(xù)，直至比較最后兩個(gè)數(shù)，將小數(shù)放前，大數(shù)放后。重復(fù)第一趟步驟，直至全部排序完成。
第一趟比較完成后，最后一個(gè)數(shù)一定是數(shù)組中最大的一個(gè)數(shù)，所以第二趟比較的時(shí)候最后一個(gè)數(shù)不參與比較；
第二趟比較完成后，倒數(shù)第二個(gè)數(shù)也一定是數(shù)組中第二大的數(shù)，所以第三趟比較的時(shí)候最后兩個(gè)數(shù)不參與比較；
依次類推，每一趟比較次數(shù)-1；
??
舉例說明：要排序數(shù)組：int[]?arr={6,3,8,2,9,1};?
for(int i=1;iarr.length;i++){
for(int j=1;jarr.length-i;j++){
//交換位置
} ? ?
參考資料：冒泡排序原理
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:
//簡單選擇排序,按自然順序
public static void selectsort(int[] array){
int min, index, temp;
for(int i = 0; i array.length - 1; i++){ // N - 1 趟
min = i;
//查找選擇最小元素值的下標(biāo)索引值
for(index = i + 1; index array.length; index++){
if(array[min] array[index])
min = index;
}
//交換
if(min != i){
temp = array[min];
array[min] = array[i];
array[i] = temp;
}
}
}
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