String Compression III

class Solution {
public:
    string encodeString(string inputStr) {
        string encoded = "";
        int index = 0;

        while (index < inputStr.size()) {
            int count = 0;
            char charToEncode = inputStr[index];

            while (index < inputStr.size() && count < 9 &&
                   inputStr[index] == charToEncode) {
                count++;
                index++;
            }

            encoded += to_string(count) + charToEncode;
        }

        return encoded;
    }
};

The given C++ code defines a method encodeString within a class Solution. This method is designed to perform a basic string compression where consecutive characters in the input string are encoded as the number of occurrences followed by the character itself.

You start with initializing an empty string encoded which eventually holds the compressed version of the input string. The process begins with an initial index set to zero. As you loop through inputStr, you count the occurrences of each character until either the character changes, the count reaches 9, or the end of the string is reached.

The method includes:

• A while loop to iterate over the inputStr.
• A nested while loop to count continuous, identical characters without exceeding 9.
• Inside the inner loop, characters are counted, and the index is incremented.
• After exiting the inner loop, the count and the character are concatenated to the encoded string.

Once all characters from the input string have been processed, the method returns the compressed string representation. The approach is efficient for long strings with repeated characters but ensures that the encoding does not exceed the character count of 9 for any sequence, shrinking larger sequences into multiple encoded segments if necessary.

class Solution {

    public String encodeString(String inputStr) {
        StringBuilder result = new StringBuilder();

        int index = 0;

        while (index < inputStr.length()) {
            int count = 0;
            char current = inputStr.charAt(index);

            while (
                index < inputStr.length() &&
                count < 9 &&
                inputStr.charAt(index) == current
            ) {
                count++;
                index++;
            }

            result.append(count).append(current);
        }

        return result.toString();
    }
}

This Java solution addresses the problem of string compression, specifically designed to compress sequences of the same character found in a given string inputStr.

The method encodeString(String inputStr) is responsible for creating the compressed version of the input string. The process involves the following steps:

1. Initialize a StringBuilder called result which is used to store the accumulating encoded string.
2. Use a while loop to traverse through each character of the input string, with an index initialized at 0.
3. Inside the loop, initialize count to 0 to represent the count of consecutive identical characters.
4. A while loop nested inside checks three conditions: the index must be within bounds of the input string, the count of consecutive characters is less than 9, and the current character at the index position matches the character held in current.
5. During each iteration of the nested loop, increment the count and index.
6. Append the count and the current character to the StringBuilder to form a part of the final encoded result.
7. Finally, convert the StringBuilder to a string and return it as the output.

This function compresses sequences of up to nine identical characters by listing the count followed by the character itself. For example, the string "aaaabbcccc" will be encoded as "4a2b3c". If an identical sequence has more than nine characters, it will start a new count for the same character beyond nine.

class Compressor:
    def compress(self, input_string: str) -> str:
        compressed = []
        index = 0

        while index < len(input_string):
            count = 0
            char = input_string[index]

            while index < len(input_string) and count < 9 and input_string[index] == char:
                count += 1
                index += 1

            compressed.append(str(count))
            compressed.append(char)

        return "".join(compressed)

The code provided is a Python class named Compressor with a method compress designed to compress a given string. The compression follows a specific pattern where consecutive characters are replaced with the count of their occurrence followed by the character itself, limiting the count to a maximum of 9.

Here's how the compression works:

• Initialize an empty list called compressed to store the compressed form of the string.
• Set up an index variable to control the position in the input string during iteration.
• Use a while loop to traverse through all characters in the input_string.
• For each character, reset a count to zero and record the char at the current index.
• Use another while loop to count occurrences of the same character, making sure not to exceed 9 consecutive characters or to go beyond the string length.
• Append the count (converted to string) and the character to the compressed list.
• Continue to the next unique character in the input string.

Finally, join all elements in the compressed list into a single string and return it.

This method effectively compresses strings by summarizing sections of repeated characters, making it useful for simple compression tasks where maximum compression isn't crucial but quick reductions are desired. Note that if a character repeats more than 9 times consecutively, it will be split into multiple groups of up to 9. This returns a compressed string that always alternates between a number (as a string) and a letter.