208. Implement Trie (Prefix Tree

class TrieNode {
    // Initialize your data structure here.
    
    public boolean isWord;
    public TrieNode[] children=new TrieNode[26];
    public TrieNode() {
        
    }
}

public class Trie {
    private TrieNode root;

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

    // Inserts a word into the trie.
    public void insert(String word) {
        TrieNode ws=root;
        for(int i=0;i<word.length();i++){
            char c=word.charAt(i);
            if(ws.children[c-'a']==null) ws.children[c-'a']=new TrieNode();
            ws=ws.children[c-'a'];
        }
        ws.isWord=true;
    }

    // Returns if the word is in the trie.
    public boolean search(String word) {
        TrieNode ws=root;
        for(int i=0;i<word.length();i++){
            char c=word.charAt(i);
            if(ws.children[c-'a']==null) return false;
            ws=ws.children[c-'a'];
        }
        return ws.isWord;
    }

    // Returns if there is any word in the trie
    // that starts with the given prefix.
    public boolean startsWith(String prefix) {
        TrieNode ws=root;
        for(int i=0;i<prefix.length();i++){
            char c=prefix.charAt(i);
            if(ws.children[c-'a']==null) return false;
            ws=ws.children[c-'a'];
        }
        return true;
    }
}