leetcode--Implement Trie (Prefix Tree)

Implement a trie with

insert

,

search

, and

startsWith

methods.

Note:

You may assume that all inputs are consist of lowercase letters

a-z

.class TrieNode {
// Initialize your data structure here.
public TrieNode() {}
Map<Character,TrieNode> next = new HashMap<Character,TrieNode>();
char c='\0';
boolean isEnd = false;
public TrieNode(char c) {
this.c = c;
}
}
public class Trie {
private TrieNode root;

public Trie() {
root = new TrieNode();
}

// Inserts a word into the trie.
public void insert(String word) {
TrieNode cur = root;
for(int i=0;i<word.length();i++){
if(!cur.next.containsKey(word.charAt(i))){
cur.next.put(word.charAt(i), new TrieNode(word.charAt(i)));
}
cur = cur.next.get(word.charAt(i));
}
cur.isEnd = true;
}

// Returns if the word is in the trie.
public boolean search(String word) {
TrieNode cur = root;
for(int i=0;i<word.length();i++){
if(cur.next.containsKey(word.charAt(i))){
cur = cur.next.get(word.charAt(i));
}else{
return false;
}
}
if(cur.isEnd) return true;
return false;
}

// Returns if there is any word in the trie
// that starts with the given prefix.
public boolean startsWith(String prefix) {
TrieNode cur = root;
for(int i=0;i<prefix.length();i++){
if(cur.next.containsKey(prefix.charAt(i))){
cur = cur.next.get(prefix.charAt(i));
}else{
return false;
}
}
return true;
}
}

// Your Trie object will be instantiated and called as such:
// Trie trie = new Trie();
// trie.insert("somestring");
// trie.search("key");