簡介

給定一個 PGM image 檔案，利用 Huffman Coding 演算法設計與實作檔案壓縮程式：

i.	Input: xxx.pgm (using IrfanView (https://www.irfanview.com/) to covert jpeg, gif, and more into pgm ASCII format)

ii.	Output: a compressed file xxx.hc

iii.	Functions: 
  a. 壓縮(Compression) <= 須說明如何將 Huffman Tree and Codes 置於檔案中

  b. 解壓縮(Uncompression)