//字典樹的java實現
    public class Trie {
        private TrieNode root;

        public Trie() {
            root = new TrieNode();
            root.wordEnd = false;
        }

        public void insert(String word) {
            TrieNode node = root;
            for (int i = 0; i < word.length(); i++) {
                Character c = new Character(word.charAt(i));
                if (!node.childdren.containsKey(c)) {
                    node.childdren.put(c, new TrieNode());
                }
                node = node.childdren.get(c);
            }
            node.wordEnd = true;
        }

        public boolean search(String word) {
            TrieNode node = root;
            boolean found = true;
            for (int i = 0; i < word.length(); i++) {
                Character c = new Character(word.charAt(i));
                if (!node.childdren.containsKey(c)) {
                    return false;
                }
                node = node.childdren.get(c);
            }
            return found && node.wordEnd;
        }

        public boolean startsWith(String prefix) {
            TrieNode node = root;
            boolean found = true;
            for (int i = 0; i < prefix.length(); i++) {
                Character c = new Character(prefix.charAt(i));
                if (!node.childdren.containsKey(c)) {
                    return false;
                }
                node = node.childdren.get(c);
            }
            return found;
        }

    }

    public class TrieNode {
        Map<Character, TrieNode> childdren;
        boolean wordEnd;

        public TrieNode() {
            childdren = new HashMap<Character, TrieNode>();
            wordEnd = false;
        }
    }