String Compression and Run-Length Encoding Quiz Quiz

Challenge your understanding of string compression concepts and run-length encoding (RLE) techniques with this quiz. Enhance your knowledge of data encoding, decoding, and optimization using string-based algorithms.

1. Identifying Run-Length Encoding Output

   If the input string is 'AAAABCCDDDD', which one of the following is the correct run-length encoded result?

   1. 3A2B2C4D
   2. 4A1B2C4D
   3. 4A2B2C4D
   4. A4B1C2D4

   Explanation: The run-length encoded result '4A1B2C4D' means four 'A's, one 'B', two 'C's, and four 'D's, which matches the structure of the input string. Options like 'A4B1C2D4' and '4A2B2C4D' misorder or miscount some runs and are therefore incorrect. '3A2B2C4D' counts the 'A's and 'B's incorrectly. Only '4A1B2C4D' correctly represents the original string using the run-length encoding method.

2. Application of String Compression

   Which situation benefits the most from applying run-length encoding for string compression?

   1. Compressing a string with mostly unique, non-repeating characters
   2. Compressing strings of random hexadecimal digits
   3. Compressing a string with many consecutive repeated characters
   4. Compressing strings containing only numeric values

   Explanation: Run-length encoding is most effective when there are many consecutive repeating characters, as it reduces the storage needed by representing those runs compactly. Strings with mostly unique characters or random digits do not compress well with RLE, as the encoded form could be the same size or even larger. The numeric nature of a string or the use of hexadecimal digits does not inherently improve RLE's effectiveness.

3. Decoding Run-Length Encoded Data

   Given the run-length encoded string '3F2G1H', what is the original uncompressed string?

   1. FFFGGH
   2. F3G2H
   3. FGHFGH
   4. FFFHHG

   Explanation: The code '3F2G1H' translates to three 'F's, two 'G's, and one 'H', which gives 'FFFGGH' as the original string. The option 'FFFHHG' mixes the order, 'FGHFGH' completely rearranges and repeats the characters, and 'F3G2H' is not a valid uncompressed string. Only 'FFFGGH' directly follows the decoding rules.

4. Evaluating Compression Efficiency

   Which of the following input strings would result in the greatest reduction in data size using run-length encoding?

   1. A1B2C3D4E5
   2. ABCDEFGHIJ
   3. ABABABABAB
   4. AAAAAAAAAA

   Explanation: A string like 'AAAAAAAAAA' contains a long run of the same character, which RLE can compress very effectively, reducing ten characters to something like '10A'. 'ABCDEFGHIJ' has no repeats, so its encoded form would be the same length or longer. 'A1B2C3D4E5' and 'ABABABABAB' do not have sufficient consecutive repeats for RLE to be efficient. Therefore, 'AAAAAAAAAA' yields the highest compression.

5. Limits of Run-Length Encoding

   What is a key limitation of run-length encoding when used for general-purpose text data compression?

   1. It only works for binary data, not text
   2. It cannot represent numeric characters in text
   3. It requires loss of information during compression
   4. It increases the file size if there are few or no repeats

   Explanation: When input data lacks consecutive repeating characters, run-length encoding can actually increase file size, as it has to insert unnecessary counts. RLE can represent any characters, including numeric ones, so that's not a limitation. The process does not inherently lose information—it's reversible. RLE works with both binary and text data, not just binary.