Monday, November 15, 2010
Sunday, November 14, 2010
Saturday, November 13, 2010
Happiness
"Happiness is a mood not a destination?"
Just heard of this quote today. Is it true?
Each one of us try to pursuit that happiness that which suited our own definition.
We are trying so hard to reach that. A dream job, a brand new car, latest iphone ...
Well, it's that happiness or just our alter ego?
May be if we accept happiness is a mood then, may be, we will be more happy ...
Friday, October 22, 2010
猴子的故事
Monday, October 11, 2010
Sunday, October 10, 2010
Wednesday, September 22, 2010
Ctrl-Alt-Del in Remote Desktop
Saturday, August 14, 2010
Number Operation
Give an array with 1 to N except 1 number. Find the missing number.
public static int FindMissingNumber(int[] a)
{
if (a == null || a.Length <= 1)
return 0;
int sum = 0;
for (int i = 0; i < a.Length; i++)
sum = sum ^ a[i] ^ (i+1);
return sum ^ (a.Length+1);
}
This solution is better:
a ={1,3} Missing 2
using XOR characteristic when XOR same= number it will become 0 : A XOR A = 0.
1st pass : 1 XOR 1 = 0
001 XOR 001 = 000
2nd pass : 0 XOR 3 XOR 2 = 1
000 XOR 011 XOR 010 = 001
Final : 1 XOR 3 = 2
001 XOR 011 = 010
* Avoid using n*(n+1)/2 – sum approach as this will introduce overflow for integer data type.
Wednesday, August 11, 2010
String Operation
Naive / Brute Force
public static bool NaiveFindString(string text, string pattern)
{
if (string.IsNullOrEmpty(text)
|| string.IsNullOrEmpty(pattern)
|| text.Length < pattern.Length)
return false;
for (int i = 0; i <= text.Length - pattern.Length; i++)
if (text.Substring(i, pattern.Length) == pattern)
return true;
return false;
}
public static bool NaiveFindStringV2(string text, string pattern)
{
if (string.IsNullOrEmpty(text)
|| string.IsNullOrEmpty(pattern)
|| text.Length < pattern.Length)
return false;
for (int i = 0; i <= text.Length - pattern.Length; i++)
{
int c = 0;
while (c < pattern.Length && pattern[c] == text[i + c])
c++;
if (c == pattern.Length)
return true;
}
return false;
}
Boyer Moore
public static int[] BuildBadChar(string pattern)
{
int[] badCharMoves = new int[256]; // ASCII
for (int i = 0; i < badCharMoves.Length; i++)
badCharMoves[i] = -1;
for (int i = 0; i < pattern.Length; i++)
badCharMoves[pattern[i]] = i;
return badCharMoves;
}
public static bool BoyerMooreFindString(string text, string pattern)
{
if (string.IsNullOrEmpty(text)
|| string.IsNullOrEmpty(pattern)
|| text.Length < pattern.Length)
return false;
int[] badCharMoves = BuildBadChar(pattern);
for (int i = 0; i <= text.Length - pattern.Length;)
{
int count= pattern.Length - 1;
char ch = char.MinValue;
while (count >=0 && pattern[count] == (ch=text[i + count]))
count--;
if (count < 0)
return true;
i = i + Math.Max(count - badCharMoves[ch],1);
}
return false;
}
Remove duplicates
public static string RemoveDuplicate(string text)
{
if (string.IsNullOrEmpty(text) || text.Length == 1)
return text;
char[] s = text.ToCharArray();
int tail = 1;
for (int i = 1; i < s.Length; i++)
{
int m = 0;
for (; m < tail; m++)
if (s[m] == s[i])
break;
if (tail == m)
{
s[tail] = s[i];
tail++;
}
}
StringBuilder sb = new StringBuilder(tail - 1);
for (int i = 0; i < tail; i++)
sb.Append(s[i]);
return sb.ToString();
}
Reverse a string
public static string Reverse(string text)
{
if (string.IsNullOrEmpty(text) || text.Length == 1)
return text;
int first = 0;
int last = text.Length - 1;
char[] s = text.ToCharArray();
while (first < last)
{
char c = s[first];
s[first] = s[last];
s[last] = c;
first++;
last--;
}
return new string(s);
}
Wednesday, July 28, 2010
Sunday, July 25, 2010
VS 2010 Keyboard Shortcuts
VS 2010 Keyboard Shortcuts for C#, VB, C++, F# Now Available in Letter (8.5x11in) and A4 (210×297mm) Print-Ready Sizes [Download]
Recursion
2 types of recursion exist:
| Tail | Non-Tail |
void Tail(int i) | void NonTail(int i) |
Tail Recursion
- The simplest case. A glorified loop.
- Can simply be replace by iterative method.
- The basic idea behind Tail Recursion is to eliminate the storage of any state information across the recursive steps. All information that would ever be needed at any single step is passed as a parameter to the function instead of being stored at some higher level in the recursion stack.
- In tail recursion, the recursive call should be the ONLY last statement, and there should be no earlier recursive calls whether direct or indirect.
- Used to implement loops in languages that do not support loop structures explicitly (e.g. prolog).
Example convert Tail recursion to iterative:
for loop syntax
for(init; condition; increment)
statement;
Tail | Iterative |
void Tail(int i) | void Tail(int i) |
Tail Recursion Examples:
public static void f1(int n)
{
Console.WriteLine(n);
if(n > 0)
f1(n - 1); //last statement with recursive call
}
public static void f3(int n)
{
if(n > 6)
{
Console.WriteLine(2*n);
f3(n – 2); //last statement with recursive call
} else if(n > 0)
{
Console.WriteLine(n);
f3(n – 1); //last statement with recursive call
}
}
Non - Tail recursion
Non Tail | Iterative |
double Power(double x, int n) | double Power(double x, int n) |
string Reverse(string s) | string Reverse(string s) |
Converting Non – Tail Recursion to Tail Recursion
- A non-tail recursive method can often be converted to a tail-recursive method by means of an "auxiliary" parameter. This parameter (A.K.A Accumulator) is used to form the result.
- The idea is to attempt to incorporate the pending operation into the auxiliary parameter in such a way that the recursive call no longer has a pending operation.
- The technique is usually used in conjunction with an "auxiliary" method. This is simply to keep the syntax clean and to hide the fact that auxiliary parameters are needed.
Non Tail | Tail |
long Factorial (int n) | long Factorial(int n) |
int Fib(int n){ | int Fib (int n) { |
Common errors
- Post increment and decrement operators must not be used since the update will not occur until AFTER the method call - infinite recursion.
public static int SumArray (int[ ] x, int index)
{
if (index == x.length)return 0;
else
return x[index] + SumArray (x, index++);
}
- Local variables must not be used to accumulate the result of a recursive method. Each recursive call has its own copy of local variables.
public static int sumArray (int[ ] x, int index)
{
int sum = 0;
if (index == x.length)return sum;
else {
sum += x[index];
return sumArray(x,index + 1);
}
}
- Wrong placement of return statement.
incorrect version (always return initial pass in result)
public static int Sum(int n, int result)
{
if (n >= 0)
Sum(n - 1, n + result);
return result;
}
correct version:
public static int Sum(int n, int result)
{
if (n == 0)
return result;
else
return Sum(n-1, n + result);
}
Saturday, July 24, 2010
Revenge of the Fallen
I’m always a big fans of tower defense style action game.
Recently found some that worth to try out:
Autobot Strong Hold [Play at here]
This game has free 50 stages to play with and the audio and graphics are awesome.
Canyon Defense [Play at here]
For this one, the graphic is so so. But it is a good time pass. You can also download this in iphone app store for free.
Robo Defense
For android lover, you can download this in the market. Very addictive game.
Optimus Prime: Sam, fate rarely calls upon us at a moment of our choosing.
Fate is in our hands, autobots transform …. and roll out!
Thursday, July 22, 2010
Color My World – Syntax highlighter
Finally found a syntax highlighter for my blogger site. It's called Syntax Highlighter [Official Site]. Duh!
Steps to enable syntax highlighter into your blog site:
1. Go to Design > Edit Html 
2. Find the syntax </head>.
3. Copy and Paste below statements BEFORE syntax </head>
<link href='http://alexgorbatchev.com/pub/sh/current/styles/shCore.css' rel='stylesheet' type='text/css'/>
<link href='http://alexgorbatchev.com/pub/sh/current/styles/shThemeRDark.css' rel='stylesheet' type='text/css'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shCore.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushCpp.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushCSharp.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushCss.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushJava.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushJScript.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushPhp.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushPython.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushRuby.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushSql.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushVb.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushXml.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushPerl.js' type='text/javascript'/>
<script src='http://alexgorbatchev.com/pub/sh/current/scripts/shBrushPowerShell.js' type='text/javascript'/>
<script language='javascript'>
SyntaxHighlighter.config.bloggerMode=true;
SyntaxHighlighter.config.clipboardSwf='http://alexgorbatchev.com/pub/sh/current/scripts/clipboard.swf';
SyntaxHighlighter.all();
</script>
&nsbp;
4. If you’re using windows live writer, you can integrate syntax highlighter using Precode Code Snippet Manager plug-in [Download here].
5. Here is example of Syntax Highlighter in action:
public void ConvertStringDecimal(string stringVal) {
decimal decimalVal = 0;
try {
decimalVal = System.Convert.ToDecimal(stringVal);
System.Console.WriteLine(
"The string as a decimal is {0}.", decimalVal);
}
catch (System.OverflowException){
System.Console.WriteLine(
"The conversion from string to decimal overflowed.");
}
catch (System.FormatException) {
System.Console.WriteLine(
"The string is not formatted as a decimal.");
}
catch (System.ArgumentNullException) {
System.Console.WriteLine(
"The string is null.");
}
// Decimal to string conversion will not overflow.
stringVal = System.Convert.ToString(decimalVal);
System.Console.WriteLine(
"The decimal as a string is {0}.", stringVal);
}
If you don’t like to use the plug-in, you can directly surrounding your code snippet with <pre> </pre>, example:
<pre class="brush: js">
/** * SyntaxHighlighter */
function foo()
{
if (counter <= 10)
return; // it works!
}
</pre>
Last, Welcome to my colorful world!
Saturday, July 10, 2010
天使的祝福
一。传说，
一个女孩的诞生，也意味着一个天使的诞生。
天使的使命是守护着女孩。
二。蜕变
女孩也长大了，变成少女。
天使还是继续默默守护着少女。
三。情愫
天使由守护，变成了爱慕。
天使已经爱上了少女。
四。心蚀
少女恋爱了。
少女已不需要天使的守护与祝福。
少女已经找到了自己的幸福。
五。诅咒
伤心的天使不再守护，不再祝福少女。
天使发现自己已经不能守护少女了。
失去了守护能力的天使，是一种诅咒。
六。幻灭
天堂是没有眼泪的。
天使的眼泪，代表着天使的终结。
流泪的天使，注定要消失。
消失前，天使献上了最后的祝福，愿少女永远幸福。
七。新生
原来天使并没有消失。
天使的终结，代表一个男人的诞生。
男人会找到他所爱的女孩。
男人会永远守护着女孩，让女孩幸福。
The Road Not Taken
Robert Frost (1874–1963). Mountain Interval. 1920.
The Road Not Taken
TWO roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;
Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,
And both that morning equally lay
In leaves no step had trodden black.
Oh, I kept the first for another day!
Yet knowing how way leads on to way,
I doubted if I should ever come back.
I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I—
I took the one less traveled by,
And that has made all the difference.
Friday, July 9, 2010
Breathe new life into your laptop: Windows Server 2008 R2 as workstation
Forget about Windows 7 and Windows Vista, Windows Server 2008 R2 is the new bad boy for your laptop.
It runs blazing fast ,uses less hardware resources and more robust. It also equips with lots of server features such as Hyper-V, IIS 7.5, PowerShell 2.0, etc.
Best of all, it is x64 bits OS (Don’t worry, your old faithful x86 apps will still run as normal).
To run Windows Server 2008 R2 as workstation on your laptop, some customizations are needed:
- Install graphics and sounds drivers after installation.
- Enable Wireless networking
- Click on Server Manager
besides your windows start button. - Inside Server Manager window, click on ‘Features’ at left panel
. - After that click on ‘Add Features’ at right panel
. - Inside Add Features Wizard window, checked ‘Wireless LAN Service’ if it is not installed.
- Click on Server Manager
- Enable Windows Audio, Windows Media Player and Windows Photo Viewer.
- Inside Add Features window (same as above), checked ‘Desktop Experience’ if it is not installed.
- After that, at Administrative Tools menu, click on ‘Services’
. - Inside Services window, start ‘’Windows Audio’ service if it is not started.
- Inside Add Features window (same as above), checked ‘Desktop Experience’ if it is not installed.
- Disable Internet Explorer enhanced security
- Inside Server Manager windows (refer above step 2), click ‘Configure IE ESC’ at Security Information right panel
- Click ‘Off’ radio button
- Inside Server Manager windows (refer above step 2), click ‘Configure IE ESC’ at Security Information right panel
- Enable hibernation
- Open a command window by typing ‘cmd’ in Run menu.
- Inside command window, type ‘powercfg.exe –h on’
- Click on power icon at lower right of your desktop (A.K.A systray)
. Click on More power options. - Inside Power Options window, click on ‘Choose what closing the lid does’
- Choose ‘Hibernate’ from drop down for ‘When I close the lid’
- Disable Shutdown Event Tracker
- At Run menu, type ‘gpedit.msc’.
- Inside Local Group Policy Editor, navigate to Computer Configuration>Administrative Templates>System
- Click on ‘Display Shutdown Event Tracker’ at right panel
- Inside Display Shutdown Event Tracker window, click ‘disable’ radio button
- Enable image thumbnails preview in windows explorer
- At Run menu, type ‘SystemPropertiesPerformance’.
- Inside Performance Options window, checked ‘Show thumbnails instead of icons’
- Open windows explorer, then at menu bar choose Tools>Folder Options
- Inside Folder Options window, unchecked ‘Always show icons, never thumbnails’
Now, stop drooling and start take action to give your old laptop a second life!
