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CSC3100 Assignment 2

Marking Criterion:

1. The full score of the assignment is 100 marks.

2. Normal submission: 100 marks are given if a submission passes both compression and decompression tests. 80 marks are given if it passes compression test only.

3. Resubmission: For normal submissions that fail in compression test, a resubmission is allowed within one week after the marking. 60 marks are given if the resubmission passes compression test. 75 marks are given if the resubmission passes both compression and decompression tests.

4. Late submission: 60 marks are given if the submission passes compression test. 75 marks are given if it passes both compression and decompression tests. No resubmission is allowed.

5. Zero mark is given if: there is no (normal or late) submission; a normal submission fails compression test and the resubmission fails compression test; a normal submission fails compression test and there is no resubmission; a late submission fails compression test.

6. In case of identical copies, both submissions will be marked as zero. Similar rules apply to other cases of plagiarism found.

Running Environment:

1. The submissions will be evaluated in Java environment under Linux platform.

2. The submission is acceptable, if it runs in any of recent versions of Java SDK environment. These versions include from Java SE 8 to the most recent Java SE 17.

3. The submission is only allowed to import three packages of (java.lang.*; java.util.*; java.io.*) included in Java SDK. No other packages are allowed.

4. In each test, the program is required to finish within 10 seconds of time for an input file no larger than 100KB, with no more than 128MB memory.

5. Each student is free to test his/her program in the evaluation platform before the submission.

Submission Guidelines:

1. Detailed submission guideline will be given in a separate manual around Nov. 15.

2. Inconsistency with or violation from the guideline leads to marks deduction.

Functional Requirement:

This assignment implements the Huffman tree (https://en.wikipedia.org/wiki/Huffman_coding), which is a powerful algorithm widely in data compression. Two programs are required.

1. HuffmanCompression.java compresses a given text file (encoded with ASCII code) using Huffman tree method with the following command:

An example of input file follows:

After constructing a Huffman tree, one file of code dictionary will be output:

The dictionary shows that the space character will encoded as “01110” (note that 10 is the ASCII code of the linefeed character. 32 is the ASCII code of the space character…)

The other output will be the compressed text:

The file gives the compressed text of the input.txt based on the dictionary shown above.

2. HuffmanDecompression.java decompresses a compressed text based on the Huffman code dictionary with the following command:

The compressed.txt and dictionary.txt are input files obtained from the compression process. The output file (“output.txt”) should have the same contents as “input.txt” used in the compression process.

Program Template:

Each submission is expected to strictly follow the template to implement the required function.

1. Modify getHuffmanCode() and getCompressedCode() in HuffmanCompression.java to implement the required compression function.

2. Modify main() in HuffmanDecompression.java to implement the required decompression function.

Appendix

1. HuffmanCompression.java

2. HuffmanDecompression.java

3. input.txt

4. dictionary.txt

5. compressed.txt

6. output.txt