ImplementCachingDictionary.java

import java.util.*;
import java.util.stream.Collectors;

public class ImplementCachingDictionary implements SpellCheckService {

    /*
    20.1
    */


    private Spell dictionary = new Spell();
    private static final int MAX_ENTRIES = 3;

    @Override
    public void service(ServiceRequest request, ServiceResponse response) {
        LinkedHashMap<String, List<String>> closest = new LinkedHashMap<>();
        closest.put(request.extractWordToCheckFromRequest(), dictionary.closest(request.extractWordToCheckFromRequest()));
        response.encodeIntoResponse(closest);
    }

    public class Spell {
        public List<String> closest(String word) {
            int kthClosest = 0;
            int entries = 0;
            Map<Integer, String> closest = new HashMap<>();
            for (String entry: dictionary) {
                Integer tmp = ComputeLevenshtein.levenschteinDistance(word, entry);
                if (entries < k) {
                    ++entries;
                    closest.put(tmp, entry);
                    if (tmp > kthClosest)
                        kthClosest = tmp;
                } else if (tmp < kthClosest) {
                    closest.remove(Collections.max(closest.keySet()));
                    closest.put(tmp, entry);
                }
            }
            return closest.entrySet()
                    .stream()
                    .map(Map.Entry::getValue)
                    .collect(Collectors.toList());
        }

        private final int k = 3;
        private final List<String> dictionary = Arrays.asList(
                "bat", "cat", "mat", "dog", "mop",
                "top", "bop", "nob", "mob", "bob"
        );

    }
}