// CSE 373, Winter 2013, Marty Stepp
// This program counts occurrences of words in a file, then
// finds the top words that occur the most times.
// The program demonstrates the use of a Map.
// It also demonstrates a "compound" collection, in this case,
// a Map of Sets.

import java.io.*;
import java.util.*;

public class Lecture03 {
	public static void main(String[] args) throws FileNotFoundException {
		// create a map of (word -> count of occurrences of that word)
		Map<String, Integer> counts = new TreeMap<String, Integer>();
		Scanner input = new Scanner(new File("gettysburg.txt"));
		while (input.hasNext()) {
			String word = input.next();
			if (!counts.containsKey(word)) {
				counts.put(word, 1);
			} else {
				int count = counts.get(word);
				count++;
				counts.put(word, count);
			}
		}
		
		// reverse the map...
		// (count -> word(s) that have that count)
		Map<Integer, Set<String>> revMap = new TreeMap<Integer, Set<String>>();
		for (String word : counts.keySet()) {
			int count = counts.get(word);
			if (!revMap.containsKey(count)) {
				revMap.put(count, new TreeSet<String>());
			}
			revMap.get(count).add(word);
		}
		
		System.out.println(revMap);
	}
}