数据压缩大作业，LZ77算法的实现，简单实用。-Data compression, LZ77 algorithm, simple and practical

Lempel–Ziv–Welch (LZW) is a universal lossless data compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. It was published by Welch in 1984 as an improved implementation of the LZ78 algorithm published by Lempel and Ziv in 1978