Since you are writing your output line by line, you don't need to store a matrix. You need a hash which maintains the number of times the word is found in a given paragraph. Therefore,
open the output file
write the key line as an ordered set (array) with tab (\t) characters in appropriate places
make a hash of all 100 keys with zero as the value
then, for each paragraph,
read from input file into a string until you find '-100'
see if each character group (until space, newline, or punctuation) is a key
if so, increment the hash value of that key. If not, ignore
write out the values to the output file as an ordered set
reset the hash values to zero
close the files
You'll want to deal with capitalization somehow, as well. :D
Don Wilde
"There's more than one level to any answer."