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LevDistance
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import java.io.*; | |
import java.sql.SQLOutput; | |
import java.util.*; | |
public class Main { | |
private static Set<String> words; | |
private static Map<String, Set<String>> neighbors; | |
private static final char[] ALPHABET = "qwertyuiopasdfghjklzxcvbnm".toCharArray(); | |
public static void main(String[] args) throws IOException { | |
BufferedReader reader = new BufferedReader(new FileReader(new File("dictionary.txt"))); | |
words = new HashSet<>(); | |
neighbors = new HashMap<>(); | |
long startTime = System.currentTimeMillis(); | |
String line; | |
while ((line = reader.readLine()) != null) { | |
words.add(line.trim().toLowerCase()); | |
} | |
System.out.println("Done adding " + words.size() + " words to the set in " + | |
(System.currentTimeMillis() - startTime) + " ms."); | |
createNeighborsMap(); | |
System.out.println("Done creating " + neighbors.size() + " neighbors map in " + | |
(System.currentTimeMillis() - startTime) + " ms."); | |
// testNeighbors(); | |
askLevDistance(); | |
} | |
private static void createNeighborsMap() { | |
for (String word : words) { | |
Set<String> neighboringWords = new HashSet<>(); | |
for (int i = 0; i < word.length(); i++) { | |
String prefix = word.substring(0, i); | |
for (int j = 0; j < ALPHABET.length; j++) { | |
String newWord = prefix + ALPHABET[j] + word.substring(i); | |
if (words.contains(newWord)) { | |
neighboringWords.add(newWord); | |
} | |
} | |
for (int j = 0; j < ALPHABET.length; j++) { | |
String newWord = prefix + word.substring(i + 1); | |
if (words.contains(newWord)) { | |
neighboringWords.add(newWord); | |
} | |
} | |
} | |
if (neighboringWords.size() > 0) { | |
neighbors.put(word, neighboringWords); | |
} | |
} | |
} | |
private static void testNeighbors() { | |
Scanner input = new Scanner(System.in); | |
while (true) { | |
System.out.print("Word: "); | |
String word = input.nextLine(); | |
System.out.println(neighbors.get(word)); | |
} | |
} | |
private static void askLevDistance() { | |
Scanner input = new Scanner(System.in); | |
while (true) { | |
System.out.print("Word 1: "); | |
String word1 = input.nextLine().toLowerCase(); | |
System.out.print("Word 2: "); | |
String word2 = input.nextLine().toLowerCase(); | |
if (word1.equals(word2)) { | |
System.out.println("FOUND with distance = 0"); | |
} else if (!neighbors.containsKey(word1)) { | |
System.out.println("Word '" + word1 + "' is not in the dictionary."); | |
} else if (!neighbors.containsKey(word2)) { | |
System.out.println("Word '" + word2 + "' is not in the dictionary."); | |
} | |
findLevDistance(word1, word2); | |
} | |
} | |
private static void findLevDistance(String start, String end) { | |
Queue<Word> wordsToVisit = new LinkedList<>(); | |
Set<String> searched = new HashSet<>(); | |
wordsToVisit.add(new Word(start, 0)); | |
searched.add(start); | |
LinkedList<Set<String>> layers = new LinkedList<>(); | |
Set<String> firstLayer = new HashSet<>(); | |
firstLayer.add(start); | |
layers.add(firstLayer); | |
Set<String> bottomLayer = firstLayer; | |
int distance = 1; | |
while (!bottomLayer.isEmpty()) { | |
// for every word, add its neighbors to the next layer | |
Set<String> nextLayer = new HashSet<>(); | |
for (String word : bottomLayer) { | |
if (neighbors.containsKey(word)) { | |
for (String neighbor : neighbors.get(word)) { | |
if (neighbor.equals(end)) { | |
System.out.println("FOUND with distance = " + distance); | |
return; | |
} else if (!searched.contains(neighbor)) { | |
nextLayer.add(neighbor); | |
searched.add(neighbor); | |
} | |
} | |
} | |
} | |
layers.addLast(nextLayer); | |
bottomLayer = nextLayer; | |
distance++; | |
} | |
/* | |
while (!wordsToVisit.isEmpty()) { | |
// remove front word of the list | |
Word front = wordsToVisit.remove(); | |
int distance = front.distance; | |
if (neighbors.containsKey(front.word)) { | |
for (String neighbor : neighbors.get(front.word)) { | |
if (!searched.contains(neighbor)) { | |
if (neighbor.equals(end)) { | |
System.out.println("FOUND with distance = " + distance + 1); | |
return; | |
} else { | |
wordsToVisit.add(new Word(neighbor, distance + 1)); | |
searched.add(neighbor); | |
} | |
} | |
} | |
} | |
}*/ | |
System.out.println("No possible path, searched until distance = " + distance); | |
} | |
private static class Word { | |
public String word; | |
public int distance; | |
public Word(String word, int distance) { | |
this.word = word; | |
this.distance = distance; | |
} | |
} | |
} |
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