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Trie.java
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82 lines (74 loc) · 2.23 KB
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package tree;
public class Trie {
private TrieNode root;
/** Initialize your data structure here. */
public Trie() {
root = new TrieNode();
}
/** Inserts a word into the trie. */
public void insert(String word) {
TrieNode node = root;
for (int i = 0; i < word.length(); i++) {
char currentChar = word.charAt(i);
if (!node.containsKey(currentChar)){
node.put(currentChar,new TrieNode());
}
node = node.get(currentChar);
}
node.setEnd();
}
/** Returns if the word is in the trie. */
public boolean search(String word) {
TrieNode node = searchPrefix(word);
return node != null && node.isEnd;
}
private TrieNode searchPrefix(String word){
TrieNode node = root;
for (int i = 0; i < word.length(); i++) {
char curLetter = word.charAt(i);
if (node.containsKey(curLetter)){
node = node.get(curLetter);
}else {
return null;
}
}
return node;
}
/** Returns if there is any word in the trie that starts with the given prefix. */
public boolean startsWith(String prefix) {
TrieNode node = searchPrefix(prefix);
return node != null;
}
public class TrieNode{
private TrieNode[] links;
private final int R = 26;
private boolean isEnd;
public TrieNode(){
links = new TrieNode[R];
}
public boolean containsKey(char ch){
return links[ch - 'a'] != null;
}
public TrieNode get(char ch){
return links[ch - 'a'];
}
public void put(char ch,TrieNode node){
links[ch -'a'] = node;
}
public void setEnd(){
isEnd = true;
}
public boolean isEnd(){
return isEnd;
}
}
public static void main(String[] args) {
String word = "ten";
String prefix = "te";
Trie trie = new Trie();
trie.insert(word);
boolean param_2 = trie.search("ta");
boolean param_3 = trie.startsWith(prefix);
System.out.printf("param_2:%b,param_3:%b",param_2,param_3);
}
}