/**
* Helper function for contains that takes in a String s and a LetterNode letter and verifies that
* the first letter of s matches the LetterNode letter. If this does not hold; returns false.
*
* @param s is the prefix being checked if it is in the dictionary
* @param letter is compared to the first letter of s to see if s is in the dictionary
*/
public boolean containsHelper(String s, LetterNode w) {
// If w's letter is equal to the first letter of s
if (w.toString().equals(s.substring(0, 1))) {
// If s has one letter and the corresponding TreeNode
// completesFullWord, then the word is in the Trie.
if (s.length() == 1) {
if (w.completesFullWord) {
return true;
} else {
return false;
}
} else {
LetterNode nextPossible = w.getNextLetter(s.substring(1, 2));
// If child LetterNode corresponding to the next letter does not exist
if (nextPossible == null) {
return false;
} else {
return containsHelper(s.substring(1), nextPossible);
}
}
}
return false;
}
/* If Trie has child corresponding to letter, then return the child.
* Else create the child and return it.
*
*/
public LetterNode getFirstLetter(String letter) {
for (int x = 0; x < myChildren.size(); x++) {
LetterNode current = myChildren.get(x);
if (current.toString().equals(letter)) {
return current;
}
}
LetterNode newLetter = new LetterNode(letter, null);
myChildren.add(newLetter);
return newLetter;
}
/**
* Helper function for containsPrefix that takes in a String s and a LetterNode letter and
* verifies that the first letter of s matches the LetterNode letter. If this does not hold;
* returns false.
*
* @param s is the prefix being checked if it is in the dictionary
* @param letter is compared to the first letter of s to see if s is in the dictionary
*/
private boolean containsPrefixHelper(String s, LetterNode letter) {
// If w's letter is equal to the first letter of s
if (letter.toString().equals(s.substring(0, 1))) {
// If s has one letter, then the prefix is in the Trie.
if (s.length() == 1) {
return true;
} else {
LetterNode nextPossible = letter.getNextLetter(s.substring(1, 2));
// If child LetterNode corresponding to the next letter does not exist
if (nextPossible == null) {
return false;
} else {
return containsPrefixHelper(s.substring(1), nextPossible);
}
}
}
return false;
}
/**
* If the prefix is in the lexicon, returns true.
*
* @param s The word to search for.
* @return True if the lexicon contains s.
*/
public boolean containsPrefix(String s) {
// Check for empty string
if (s == "") {
return false;
}
// Indicates if the Trie has a child corresponding to the first letter of s.
// By default hasFirstLetter's value is false.
boolean hasFirstLetter = false;
for (int x = 0; x < myDictionary.myChildren.size(); x++) {
LetterNode current = myDictionary.myChildren.get(x);
if (current.toString().equals(s.substring(0, 1))) {
hasFirstLetter = true;
}
}
return hasFirstLetter
&& containsPrefixHelper(s, myDictionary.getFirstLetter(s.substring(0, 1)));
}