CSE1020 Lab 11: Sets and Maps

You do not need to submit this lab, BUT TRY TO FINISH IT ON YOUR OWN ANYWAY. Three different solutions will be posted on Friday, November 25.

Sets and Maps

Write a program that counts the number of gold, silver, and bronze medals won by each country in the Olympic Games. Your program should read the input from a file (see program at the bottom of the page).

Assume that the input is line based, with the results for an event given as a comma-delimited list of fields:

men's curling, Canada, Finland, USA

where the first field is the event name, the second field is the gold medal winning country, the third field is the silver medal winning country, and the fourth field is the bronze medal winning country (note that this problem ignores the case where a tie has occurred).

Your program should output the medal count for each country in order of the number of gold medals won. If there is tie for the number of gold medals won, the countries that tied should be listed in alphabetic order.

Sample Input: (based on the Turin 2006 Winter Olympics)

men's curling, Canada, Finland, USA
women's curling, Sweden, Switzerland, Canada
men's ice hockey, Sweden, Finland, Czech Republic
women's ice hockey, Canada, Sweden, USA
men's skeleton, Canada, Canada, Switzerland
women's skeleton, Switzerland, Great Britain, Canada
men's luge, Italy, Russia, Latvia
women's luge, Germany, Germany, Germany
mixed luge, Austria, Germany, Italy
men's 4 x 7.5 km relay biathlon, Germany, Russia, France
men's 12.5 km pursuit biathlon, France, Norway, Germany
men's 20 km individual biathlon, Germany, Norway, Norway
women's 4 x 6 km relay biathlon, Russia, Germany, France
women's 10 km pursuit biathlon, Germany, Germany, Russia
women's 15 km individual biathlon, Russia, Germany, Russia
men's halfpipe snowboarding, USA, USA, Finland
women's halfpipe snowboarding, USA, USA, Norway
some made up event, Canada, Bosnia and Herzegovina, Serbia and Montenegro

Sample output: Your program should output the country name using 25 spaces, and each number of medals using 3 spaces.

                   Canada  4  1  2
                  Germany  4  5  2
                   Russia  2  2  2
                   Sweden  2  1  0
                      USA  2  2  2
                  Austria  1  0  0
                   France  1  0  2
                    Italy  1  0  1
              Switzerland  1  1  1
   Bosnia and Herzegovina  0  1  0
           Czech Republic  0  0  1
                  Finland  0  2  1
            Great Britain  0  1  0
                   Latvia  0  0  1
                   Norway  0  2  2
    Serbia and Montenegro  0  0  1

Hints

• You might choose to solve the easier problem of only counting the printing the number of gold medals won by the countries.
• There are many possible solutions to the problem of keeping track of the number of gold, silver, and bronze medals won by each country. Two obvious solutions are: (1) use a Map<String, List<Integer>> where the country name is mapped to a list of medal counts (each list has size 3, and element 0 holds the number of gold medals won, element 1 holds the number of silver medals won, and element 2 holds the number of bronze medals won); (2) use three separate Map<String, Integer>s where the first map maps the country name to the number of gold medals won, the second map maps the country name to the number of silver medals won, and the third map maps the country name to the number of bronze medals won.
• Another problem you must solve is how to obtain the set of country names (which you do not know ahead of time). One way to solve this problem is to update all of the maps the first time you see a country name. Consider the sample input shown above: the first line in the file indicates that Canada has won a gold medal in men's curling. Obviously, you need to update the map of gold medals won for Canada, but you should also insert a zero into the maps of silver medals won and bronze medals won for Canada.
• Generating the output requires the number of gold medals won by all of the countries sorted in reverse order. One way to do this is to create a TreeSet of the number of gold medals won; this generates a set sorted in ascending order. Then use the descendingSet method in TreeSet to produce a new set sorted in descending order.
• Once you have the set of the number of gold medals won by all of the countries sorted in descending order, you need to find all of the countries that have won each number of gold medals. For example, in the sample output above, we needed to find Canada and Germany, both of who won 4 gold medals.
• Use printf to format the output.
• You can start with the program shown below:

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

public class MedalCount
{
   public static void main(String[] args) throws IOException
   {
      PrintStream out = System.out;

      // read the input using a scanner
      final String INPUT_NAME = "/cse/course/1020/medals.txt";
      Scanner in = new Scanner(new File(INPUT_NAME));

      // YOUR CODE GOES HERE TO DECLARE SOME COLLECTIONS

      while (in.hasNextLine())
      {
         String line = in.nextLine();
         if (line.isEmpty())
         {
            continue;
         }
         // YOUR CODE GOES HERE TO READ IN THE FILE
         //    AND POPULATE THE COLLECTIONS


      }

      // YOUR CODE GOES HERE TO OUTPUT THE RESULTS

   }
}