替换单词

在英语中，有一个叫做 词根(root) 的概念，它可以跟着其他一些词组成另一个较长的单词——我们称这个词为 继承词(successor)。例如，词根an，跟随着单词 other(其他)，可以形成新的单词 another(另一个)。现在，给定一个由许多词根组成的词典和一个句子，需要将句子中的所有继承词用词根替换掉。如果继承词有许多可以形成它的词根，则用最短的词根替换它。需要输出替换之后的句子。
示例 1：

输入：dictionary = [“cat”,“bat”,“rat”], sentence = “the cattle was rattled by the battery”
输出：“the cat was rat by the bat”

class Solution {
    class TrieNode{
        TrieNode []children;
        boolean isWord;
        public TrieNode(){
            children = new TrieNode[26];
        }
    }
    public String replaceWords(List<String> dictionary, String sentence) {
        TrieNode root = builder(dictionary);
        StringBuilder sb = new StringBuilder();
        String []words = sentence.split(" ");
        for(int i = 0; i < words.length; i++){
            String temp = searchPrefix(root,words[i]);
            if(!temp.isEmpty()){
                words[i] = temp;
            }
        }
        return String.join(" ",words);
    }
    public TrieNode builder(List<String> dictionary){
        TrieNode root = new TrieNode();
        for(String s : dictionary){
            TrieNode node = root;
            for(char ch : s.toCharArray()){
                if(node.children[ch - 'a'] == null){
                    node.children[ch - 'a'] = new TrieNode();
                }
                node = node.children[ch - 'a'];
            }
            node.isWord = true;
        }
        return root;
    }
    public String searchPrefix(TrieNode root,String words){
        TrieNode node = root;
        StringBuilder sb = new StringBuilder();
        for(char ch : words.toCharArray()){
            if(node.isWord || node.children[ch - 'a'] == null){
                break;
            }
            sb.append(ch);
            node = node.children[ch - 'a'];
        }
        return node.isWord ? sb.toString() : "" ;
    }
}