只包含英文小写字母的trie树的java实现

 * TrieNode.java
 * Created by shenhuaze on 2018/5/20.
 */
public class  {
    TrieNode[] children;
    boolean isLeaf;
    public () {
        this.children = new TrieNode[26];
        this.isLeaf = false;
    }
}

 * Trie.java
 * Created by shenhuaze on 2018/5/20.
 */
public class Trie {
    TrieNode root;
    public Trie() {
        // do intialization if necessary
        root = new TrieNode();
    }

    /*
     * @param word: a word
     * @return: nothing
     */
    public void insert(String word) {
        // write your code here
        TrieNode curr = root;
        for (int i = 0; i < word.length(); i++) {
            int offset = word.charAt(i) - 'a';
            if (curr.children[offset] == null) {
                curr.children[offset] = new TrieNode();
            }
            curr = curr.children[offset];
        }
        curr.isLeaf = true;
    }

    /*
     * @param word: A string
     * @return: if the word is in the trie.
     */
    public boolean search(String word) {
        // write your code here
        TrieNode curr = root;
        for (int i = 0; i < word.length(); i++) {
            int offset = word.charAt(i) - 'a';
            if (curr.children[offset] == null) {
                return false;
            }
            curr = curr.children[offset];
        }
        return curr.isLeaf;
    }

    /*
     * @param prefix: A string
     * @return: if there is any word in the trie that starts with the given prefix.
     */
    public boolean startsWith(String prefix) {
        // write your code here
        TrieNode curr = root;
        for (int i = 0; i < prefix.length(); i++) {
            int offset = prefix.charAt(i) - 'a';
            if (curr.children[offset] == null) {
                return false;
            }
            curr = curr.children[offset];
        }
        return true;
    }
}

 * DemoTest.java
 * Created by shenhuaze on 2018/5/20.
 */
public class DemoTest {
    public static void main(String[] args) {
        Trie trie = new Trie();
        trie.insert("hello");
        System.out.println(trie.search("hello"));
        System.out.println(trie.startsWith("hell"));
        System.out.println(trie.search("world"));
    }
}