Text Compression V2

For this challenge, you will write a program which can compress text, and also decompress its own compression scheme.

Your program will first receive the decompressed text, a capital “D” followed by 1 kB (1000 B) of space separated lowercased words from the first 50 entries in the Byte Heist word list. It should compress the text with a factor of at least 2:1; in other words, its output may be no more than 500 B.

Your program will then receive a capital “C” followed by its own compressed text, and should output the original decompressed text.