Word Counts (WC)

Given an input string counts the number of occurences of each word in the string. All non characters (not in [a-z] or [A-Z]) are replaced with a blank, and all upper-case characters are converted to lower case. A word is a maximal contiguous sequence of characters in the resulting string.

The output is a sequence of pairs, each consisting of a string (word) and a count of how many times it appears. Ordering does not matter.

Default Input Distributions

Instances consist of both synthetic and real strings.

The large instances are:

• A trigram string of length 250 Million, generated with:
  trigramString 250000000 <filename>

• etext99 is text from the project Guttenberg. It has about 105 Million characters.

• wikipedia250M.txt is a sample from wikipedia’s xml source files. It has exactly 250 million characters.

The small instances are:

• A trigram string of length 25 Million, generated with:
  trigramString 25000000 <filename>

• wikisamp.xml is a sample from wikipedia’s xml source files. It has exactly 100 million characters.

Input and Output File Formats

The input is a text file and output need to be in the sequence file format, with type StringIntPair.