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EditStepLadders.java
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EditStepLadders.java
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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class EditStepLadders {
private static final BufferedReader reader = new BufferedReader(
new InputStreamReader(System.in));
private static void add(List<String> list, Set<String> dict, String word,
String newWord) {
if (newWord.compareTo(word) < 0 && dict.contains(newWord)) {
list.add(newWord);
}
}
private static List<String> adjacent(Set<String> dict, String word) {
List<String> words = new ArrayList<>();
char[] wordArr = word.toCharArray();
for (int i = 0; i <= word.length(); ++i) {
for (char c = 'a'; c <= 'z'; ++c) {
add(words, dict, word, new StringBuilder().append(wordArr, 0, i)
.append(c)
.append(wordArr, i, wordArr.length - i).toString());
if (i < word.length()) {
add(words, dict, word,
new StringBuilder().append(wordArr, 0, i)
.append(c)
.append(wordArr, i + 1,
wordArr.length - i - 1)
.toString());
}
}
if (i < word.length()) {
add(words, dict, word,
new StringBuilder().append(wordArr, 0, i)
.append(wordArr, i + 1, wordArr.length - i - 1)
.toString());
}
}
return words;
}
private static int solve(Set<String> dict) {
List<String> sorted = new ArrayList<>(dict);
sorted.sort((x, y) -> x.compareTo(y));
Map<String, Integer> lengths = new HashMap<>();
Integer answer = 1;
for (String word : sorted) {
Integer max = 1;
for (String source : adjacent(dict, word)) {
Integer length = lengths.get(source);
max = Math.max(max, length != null ? length + 1 : -1);
}
lengths.put(word, max);
answer = Math.max(max, answer);
}
return answer;
}
public static void main(String[] args) throws IOException {
Set<String> dict = new HashSet<>();
String currentLine;
while ((currentLine = reader.readLine()) != null &&
!currentLine.trim().isEmpty()) {
dict.add(currentLine.trim());
}
System.out.println(solve(dict));
}
}