Lets Ruby!

I have been working mostly in Java for the past 4 years and my new work demands me to learn Ruby. So I've started looking into it for the past week and thought I would share my learning process so that it would be useful for someone out there. And thats the objective of this series of posts for someone having a Java background and wanting to learn Ruby.

Lets get into business. I am really excited to see the way Ruby language syntax is and I am eager to learn this mouth-watering scripting language of coolest nature. During my initial analysis, I learnt that Ruby is,

1. Implemented in many other high level languages such as C, Java, .Net etc.,
2. Is relatively slower.
3. Ruby is a high level language made of a high level language.
4. Not suitable for large applications.
5. Completely open source and is in a budding state.
6. Has a framework called Rails which is good for Agile development
7. Community out there is getting better day by day and finding help immediately should not be a problem as time goes by.
8. Has significant changes between releases which many developers wont welcome right away.
9. Running time cannot be easily estimated since the language has several underlying implementation in several languages. But there are various profilers available to test them.
10. Books are always outdated by the time when you finish them.

Now that the premise being established on what Ruby is, we shall learn it and have a comparison/understanding on how it relates to Java.

Cheers,

Bragaadeesh.

Java Program to reverse a Singly Linked List

Hi folks,

I have written an efficient way to reverse a Singly Linked List using three pointers/nodes for traversal/temporary purposes. I have given a pictorial representation of what happens with near, mid and far pointer. The program is mostly self explanatory. Remember, we are using our implementation of Singly Linked List. You may visit this link if you need that class.

Note : You may click on the above image to get a clearer picture.

Now, for the source code.


Cheers,
Bragaadeesh.

Java/C++ Program to reverse words in a sentence but still maintain the space position

This is a slight modification to the previous program. Here we should maintain the space as well. For doing that, I am simultaneously tracking the spaces and the words. I have made an assumption that there wont be any trailing or leading spaces in the sentence as such. Even if its there, a slight tweak of the following code would give me the output i desire.

package dsa.stringmanipulation;

import java.util.ArrayList;
import java.util.List;

public class RevWordWhiteSpace {

public static final String SPACE = " ";

private List<Integer> spaceTracker = new ArrayList<Integer>();
private List<String> wordTracker = new ArrayList<String>();

public static void main(String args[]){
RevWordWhiteSpace rev = new RevWordWhiteSpace();
System.out.println(rev.getRevWithWhiteSpace("This     should  maintain the space in place"));
}

/*
* Lets assume that our input text will not have any spaces before and after
*/
public String getRevWithWhiteSpace(String inputText){
if(inputText!=null && inputText.length()>0){
int lenOfText = inputText.length();
if(lenOfText==1){
return inputText;
}else{
constructLists(inputText);
StringBuilder output = new StringBuilder();
for(int i=wordTracker.size()-1,j=0; i>0; i--,j++){
output.append(wordTracker.get(i));
output.append(constructSpace(spaceTracker.get(j)));
}
output.append(wordTracker.get(0));
return output.toString();
}
}else{
System.out.println("Invalid Sentence");
return null;
}
}

private CharSequence constructSpace(Integer integer) {
String op="";
for(int i=0;i<integer;i++){
op+=" ";
}
return op;
}

private void constructLists(String inputText) {
int tempBufSpace = 0;
String bufWord = "";
for(int i=0;i<inputText.length();i++){
if(inputText.charAt(i)!=' '){
if(tempBufSpace>0){
spaceTracker.add(tempBufSpace);
tempBufSpace=0;
}
bufWord+=inputText.charAt(i);
}else{
if(bufWord.length()>0){
wordTracker.add(bufWord);
bufWord = "";
}
tempBufSpace++;
}
}
if(bufWord.length()>0){
wordTracker.add(bufWord);
}
}
}

//The output produced would be
//place     in  space the maintain should This

Also code in C++,

#include <iostream>
#include <string.h>

using namespace std;

void str_rev(char s[], int start, int end)
{
    int len = end - start;
    for(int i=0;i<len/2;i++)
    {
        char t = s[i+start];
        s[i+start] = s[end-i-1];
        s[end-i-1] = t;
    }
}

int main()
{
    char a[] = "my     name is prabhu";
    cout << "[" << a << "] ==> ";
    str_rev(a,0,strlen(a));

    cout << "[" << a << "] ==> ";

    int start_index = 0;
    for(size_t i=0;i<=strlen(a);i++)
    {
      if(a[i] == ' ' || a[i] == '\0')
      {
         str_rev(a,start_index,i);
         start_index = i+1;
      }
    }
    cout << "[" << a << "] ==> ";
    char b[strlen(a)+1];
    int i=0, k=0, j=strlen(a)-1;
    while(a[i] != '\0')
    {
        if(a[i] != ' ')
            b[k++] = a[i];
        else
        {
            while(a[j] != ' ' && j>=0)
                j--;
            while(a[j--] == ' ' && j>=0)
                b[k++] = ' ';
        }
        i++;
    }
    b[k] = '\0';
    cout << "[" << b << "]" << endl;
  
    return 0;
}

Cheers,
Bragaadeesh.