Method decompress

src/main/java/com/thealgorithms/compression/LZ78.java:113–135

Decompresses a list of LZ78 tokens back into the original string. @param compressedData The list of Token objects. Must not be null. @return The original, uncompressed string.

(List<Token> compressedData)

     * @return The original, uncompressed string.
     */
    public static String decompress(List<Token> compressedData) {
        if (compressedData == null || compressedData.isEmpty()) {
            return "";
        }

        StringBuilder decompressedText = new StringBuilder();
        Map<Integer, String> dictionary = new HashMap<>();
        int nextDictionaryIndex = 1;

        for (Token token : compressedData) {
            String prefix = (token.index == 0) ? "" : dictionary.get(token.index);

            if (token.nextChar == END_OF_STREAM) {
                decompressedText.append(prefix);
            } else {
                String currentPhrase = prefix + token.nextChar;
                decompressedText.append(currentPhrase);
                dictionary.put(nextDictionaryIndex++, currentPhrase);
            }
        }

        return decompressedText.toString();
    }
}