簡單的Trie前綴樹實現

import java.util.LinkedList;
import java.util.List;

class TrieNode {
    List<TrieNode> children = new LinkedList<>();
    boolean isEnd;
    char item = ' ';

    public TrieNode() {
    }

    public TrieNode(char item) {
        this.item = item;
    }

    public void addChild(char ch) {
        TrieNode insertNode = new TrieNode(ch);
        children.add(insertNode);
    }

    public TrieNode getChild(char ch) {
        for (TrieNode node : children) {
            if (node.item == ch) {
                return node;
            }
        }
        return null;
    }
}

public class Trie {
    private TrieNode root;

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

    public void insert(String word) {
        if (search(word)) {
            return;
        }

        TrieNode curr = root;
        for (int i = 0; i < word.length(); i++) {
            if (curr.getChild(word.charAt(i)) == null) {
                curr.addChild(word.charAt(i));
            }
            curr = curr.getChild(word.charAt(i));
        }
        curr.isEnd = true;
    }

    public boolean search(String word) {
        TrieNode curr = root;
        for (int i = 0; i < word.length(); i++) {
            if (curr.getChild(word.charAt(i)) == null) {
                return false;
            }
            curr = curr.getChild(word.charAt(i));
        }
        return curr.isEnd;
    }

    public boolean startsWith(String prefix) {
        TrieNode curr = root;
        for (int i = 0; i < prefix.length(); i++) {
            if (curr.getChild(prefix.charAt(i)) == null) {
                return false;
            }
            curr = curr.getChild(prefix.charAt(i));
        }
        return true;
    }

    public static void main(String[] args) {
        Trie trie = new Trie();
        trie.insert("hello");
        trie.insert("world");

        System.out.println(trie.search("hello"));
        System.out.println(trie.startsWith("he"));
    }
}