Java - Compressed String

Question

Given a string, I want to compress the string based on each character's number of consecutive occurrences next to it. For example, let's say we have a string like "abaasass". 'a' occurs one time, 'b' occurs one time, 'a' occurs two times consecutively, 's' occurs one time, 'a' occurs one time, and 's' occurs two times consecutively. The method should then return a string like "aba2sas2".

This is what I have so far:

public static String compressedString(String message) {
        StringBuilder compressedString = new StringBuilder();
        int total = 0;
        for (int i = 0; i < message.length() - 1; i++){
            if (message.charAt(i) == message.charAt(i+1)){
                total += 2;
                compressedString.append(message.charAt(i)).append(total);
            }
            else {
                compressedString.append(message.charAt(i));
            }
            total = 0;
        }
        return compressedString.toString();
    }

It instead returns: "aba2asas2" which is somewhat close, anyone sees the issue?

I see a host of issues. Try putting in a string with 3 or more consecutive characters. — Robby Cornelissen
– Robby Cornelissen, Commented Jul 19, 2021 at 2:33
A quick google for Java run length encoding should bring up a plethora of correct implementations. — Robby Cornelissen
– Robby Cornelissen, Commented Jul 19, 2021 at 2:34

Sither Tsering · Accepted Answer · 2021-07-19 02:48:14Z

2

public static String compressedString(String message) {
    StringBuilder compressedString = new StringBuilder();
    int total = 1;
    for (int i = 0; i < message.length() - 1; i++){
        if (message.charAt(i) == message.charAt(i+1)){
            total++;
        }
        else if(total==1){
            compressedString.append(message.charAt(i));
        }
        else 
        {
            compressedString.append(message.charAt(i)).append(total);
            total = 1;
        }
    }
    if(message.charAt(message.length()-2) != message.charAt(message.length()-1)
        compressedString.append(message.charAt(message.length()-1));
    else
        compressedString.append(message.charAt(message.length()-1)).append(total);

    return compressedString.toString();
}

edited Jul 19, 2021 at 2:48

answered Jul 19, 2021 at 2:41

Sither Tsering

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Comments

MattDog_222 Overwatch · Accepted Answer · 2021-07-19 02:50:14Z

2

public static String compressedString(String message)
{
    String result = "" ;
    
    for ( int i = 0, t = message.length() - 1 ; i < t ; )
    {
        String letter = String.valueOf( message.charAt(i) ) ;
        int currentChain = consec( i, message ) ;
        
        result += ( currentChain > 1 ? ( letter + currentChain ) : letter ) ;
        
        i += currentChain ;

    }
    return result ;
}

private static int consec( int startIndex, String text )
{
    int chain = 1 ;
    
    for( int i = startIndex ; i < text.length() - 1 ; ++i )
    {
        if( text.charAt(i) == text.charAt(i+1) )
            chain++ ;
        else
            break ;
    }
    
    return chain ;
}

answered Jul 19, 2021 at 2:50

MattDog_222 Overwatch

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Comments

Michael O'Grady · Accepted Answer · 2021-10-18 16:45:35Z

0

This is your solution for your question

static void compressedString(String str) {
    int n = str.length();
    for (int i = 0; i < n; i++) {

        // Count occurrences of current character
        int count = 1;
        while (i < n - 1 && str.charAt(i) == str.charAt(i + 1)) {
            count++;
            i++;
        }

        if (count == 1) {
            System.out.print(str.charAt(i));
        } else {
            System.out.print(str.charAt(i));
            System.out.print(count);
        }
    }
}

public static void main(String[] args) {
    String str = "abaasass";
    compressedString(str);
}

answered Oct 18, 2021 at 16:45

Michael O'Grady

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