单词查找树

import java.util.ArrayList;
import org.junit.Test;

public class TriNode{
    private static final int R=256;
    private static final ArrayList<String> keysWithPrefix=new ArrayList<String>();
    
    public static void put(Node x,String word){
        if(word.length()==0) return;
        for(int i=0;i<word.length();i++){
            char key=word.charAt(i);
            if(x.next[key]==null){
                x.next[key]=new Node();
            }
            x=x.next[key];
        }
        x.flag=true;
    }

    public static void query(Node x,String pre){
        for(int i=0;i<pre.length();i++){
            char ch=pre.charAt(i);
            if(x.next[ch]==null) return;
            x=x.next[ch];
        }
        collect(x,pre);
    }
    private static void collect(Node x,String pre){
        if(x==null) return;
        if(x.flag!=false){
            keysWithPrefix.add(pre);
            
        }
        for(char c=0;c<R;c++){
            collect(x.next[c],pre+c);
        }
    }
    static class Node{
        private Node[] next=new Node[R];
        private boolean flag=false;
    }
    @Test
    public void test(){
        Node root=new Node();
        String[] text={"by","sea","sell","sells","shell","shells","she","sho"};
        for(int i=0;i<text.length;i++){
            put(root,text[i]);
        }
        query(root,"se");
        System.out.println(keysWithPrefix);
    }
    
    
}