12/30/10

12/28/10

Parent-Child Communication Using Pipes in UNIX

This is the simplest of program that you can get.

Here the parent-child communicates over a pipe.

 NOTE:
if the child wants to communicate to the parent then it will have to closes(fd[0]) and parent will closes(fd[1]).

 this will only work UBUNTU, LINUX(RedHat) , Solaris, FreeBDS etc all UNIX VERSIONS. DONT TRY to use it on any compiler like gcc,turbo c, etc...

 Send data from Parent to Child over a pipe:


12/27/10

12/20/10

Codeforces #47, Problem E 

1:  import java.io.BufferedReader;  
2:  import java.io.IOException;  
3:  import java.io.InputStreamReader;  
4:  import java.util.HashMap;  
5:  public class Main {  
6:       public static void main(String[] args) throws IOException {  
7:            BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));  
8:            String ans=bf.readLine();  
9:            String var[]=ans.split(" ");  
10:            HashMap<Integer, Double> val=new HashMap<Integer, Double>();  
11:            double dx=0;  
12:            int cnt=0;  
13:            double rt1=0;  
14:            double rt2=0;  
15:            val.put(null, (double)1);  
16:            val.put(null, (double) 2);  
17:            for(double i=1;i<=Integer.parseInt(var[0]);i++){  
18:                 for(double j=1;j<=Integer.parseInt(var[1]);j++){  
19:                      dx= Math.pow(2*i, 2)-(4*j);  
20:                      if(dx>0){  
21:                           rt1= (((-2*i)+ Math.sqrt(dx)))/2;  
22:                           rt2= (((-2*i) - Math.sqrt(dx)))/2;  
23:                           if(val.get(cnt)==null){  
24:                                cnt=cnt+1;  
25:                                val.put(cnt,(double)rt2);  
26:                           }  
27:                           if(val.get(cnt)==null){  
28:                                cnt=cnt+1;  
29:                                val.put(cnt,(double)rt1);  
30:                           }  
31:                           if(val.containsValue(rt1) &&val.containsValue(rt2)){  
32:                           }else if(val.containsValue(rt1)){  
33:                                cnt=cnt+1;  
34:                                val.put(cnt,(double)rt2);  
35:                           }else if(val.containsValue(rt2)){  
36:                                cnt=cnt+1;  
37:                                val.put(cnt,(double)rt1);  
38:                           }else{  
39:                                cnt=cnt+2;  
40:                           val.put(cnt,(double)rt1);  
41:                           val.put(cnt,(double)rt2);  
42:                           }  
43:                      }else if(dx==0){  
44:                           rt1=(double) ((-2*i)/2);  
45:                           if(val.get(1)==null){  
46:                                cnt=cnt+1;  
47:                                val.put(cnt,(double) rt1);       
48:                           }  
49:                           if(val.containsValue(rt1)){   
50:                           }else{  
51:                                cnt=cnt+1;  
52:                                val.put(cnt,(double)rt1);  
53:                           }  
54:                      }  
55:                 }  
56:            }  
57:            System.out.println(cnt);  
58:       }  
59:  }

12/19/10

HashMap simple usage and understanding

Map is an object that stores key/volume pairs. Given a key, you can find its value. Keys must be unique, but values may be duplicated.
The HashMap class uses a hash table to implementation of the map interface. This allows the execution time of basic operations, such as get() and put() to be constant.
An example is below:
Q. Find the numbers Divisible by an array of numbers ie div[] between a range ie from 1 to N?
Ans.  This can be solved using many ways, but we will be solving using HashMap which will help u understand the concept of HashMap in a better way..

 NOTE:
For this u can use your command prompt, eclipse, netbeans or any IDE that supports JAVA. Using eclipse is much easier.


CODE :

 
1:  import java.util.HashMap; 

2:  public class Main { 

3:    public static int usingHashmap(int N,int div[]){ 

4:      int count=0; 

5:      HashMap<Integer, Integer> key=new HashMap<Integer, Integer>(); 

6:      for(int i=1;i<N;i++){ 

7:        key.put(i, i); 

8:      } 

9:      for(int i=0;i<div.length;i++){ 

10:        for(int k=1;k<N;k++){ 

11:        if(key.get(k)==null){ 

12:          key.put(k, -1); 

13:        } 

14:          if(key.get(k)%div[i]==0){ 

15:            count++; 

16:            key.remove(k); 

17:          } 

18:        } 

19:      } 

20:      System.out.println(count); 

21:      return count; 

22:    } 

23:    public static void main(String[] args) { 

24:      new Main().usingHashmap(50, new int[]{3,2}); 

25:    } 

26:  }

12/4/10

Detecting a Cookie

Here is a piece of code that can help people detect cookies. Cookies play an important part in the website.
*****************#####*****************
JS Code:
window.onload = showCookies;

 function showCookies() {
    var outMsg = "";

     if (document.cookie == "") {
        outMsg = "There are no cookies here";
    }
    else {
        var thisCookie = document.cookie.split("; ");
        for (var i=0; i<thisCookie.length; i++) {
            outMsg += "Cookie name is '" + thisCookie[i].split("=")[0];
            outMsg += "', and the value is '" + thisCookie[i].split("=")[1] + "'<br />";
        }
    }
    document.getElementById("ELEMENT ID").innerHTML = outMsg;
}
*****************#####*****************


11/29/10

11/28/10

Roll Overs in HTML

Below is a code which helps u create a roll over. for that u need to have a folder (in which the images will be there).


Roll overs are like slide show of images (or anything u want), in which u press a button and the image gets changed. The code below will help u make a roll over just like that u have in Facebook. so now if u want u can shoe others that u have a roll over made by you and which is same as FB.


11/23/10

Javascript Smarter Links

Here is a piece of code which when you use will make your link in the website SMARTER.


This piece of code i used it during my internship and it was well appreciated by the company as it made the user know that the content that they are trying to visit is out of their domain.