Day-23 Stream of Characters

class StreamChecker {
    
    class Trie{
        Trie[] next=new Trie[26];
        boolean end;
    }
    
    Trie root;
    List<Integer> query;
    
    public StreamChecker(String[] words) {
        root=new Trie();
        query=new ArrayList<>();
        
        for(String s:words){
            char[] c=s.toCharArray();
            Trie t=root;
            for(int i=c.length-1;i>=0;i--){
                if(t.next[c[i]-'a']==null){
                    t.next[c[i]-'a']=new Trie();
                }
                t=t.next[c[i]-'a'];
            }
            t.end=true;
        }
    }
    
    public boolean query(char letter) {
        query.add(letter-'a');
        Trie t=root;        
        int i=query.size()-1;
        while(i>=0){
            t=t.next[query.get(i)];
            if(t!=null && t.end){
                return true;
            }
            else if(t==null){
                return false;
            }
            i--;
        }
        
        return false;
    }
}

/**
 * Your StreamChecker object will be instantiated and called as such:
 * StreamChecker obj = new StreamChecker(words);
 * boolean param_1 = obj.query(letter);
 */