Read the MAL into a data structure that supports keyed lookups, for example a hash table.
If you knew that all acronyms were in parens, then you could use a regular expression and then iterate through the match collection. But since you don't, you should probably just read the file into a string, use some string member function to split the string into an array of words, and then do a keyed lookup of each word for a match in your lookup table. Since 90% have parens, you should look for words surrounded by parens and strip them off before doing the lookup.