需要一些关于C ++中简单无损压缩算法的想法

I'm taking an intro to programming course and one of our assignments is to write a lossless compression program in C++. The only limitations we have are that we can not use the STL, static variables, or global variables. A lot of the compression algorithms I have found require use of map/multimap which I am not allowed to use so Huffman encoding and LZW are pretty much out of the question unless I can write my own map class and get it to work.I'm taking an intro to programming course and o