ImplementTrie

class TrieNode {
    char character;
    TrieNode[] alphabet;
    boolean endsWord;
 
    public TrieNode(char character) {
        this.character = character;
        alphabet = new TrieNode[26];
        endsWord = false;
    }
}
 
public class ImplementTrie {
    TrieNode root = new TrieNode('#');
 
    public void insert(String word) {
        TrieNode currentNode = root;
 
        for (int i = 0; i < word.length(); i++) {
            char nextCharacter = word.charAt(i);
            int index = nextCharacter - 'a';
 
            if (currentNode.alphabet[index] == null) {
                currentNode.alphabet[index] = new TrieNode(nextCharacter);
            }
            currentNode = currentNode.alphabet[index];
        }
        currentNode.endsWord = true;
    }
 
    public boolean search(String word) {
        TrieNode currentNode = root;
 
        for (int i = 0; i < word.length(); i++) {
            char nextCharacter = word.charAt(i);
            int index = nextCharacter - 'a';
 
            if (currentNode.alphabet[index] == null) {
                return false;
            }
            currentNode = currentNode.alphabet[index];
        }
        return currentNode.endsWord;
    }
 
    public boolean startsWith(String word) {
 
        TrieNode currentNode = root;
 
        for (int i = 0; i < word.length(); i++) {
            char nextCharacter = word.charAt(i);
            int index = nextCharacter - 'a';
 
            if (currentNode.alphabet[index] == null) {
                return false;
            }
            currentNode = currentNode.alphabet[index];
        }
        return true;
    }
 
    public static void main(String[] args) {
        ImplementTrie trie = new ImplementTrie();
 
        trie.insert("apple");
        trie.insert("banana");
        trie.insert("carrot");
 
        System.out.println(trie.search("apple")); // true
        System.out.println(trie.search("banana")); // true
        System.out.println(trie.search("carrot")); // true
        System.out.println(trie.search("orange")); // false
 
        System.out.println(trie.startsWith("app")); // true
        System.out.println(trie.startsWith("ban")); // true
        System.out.println(trie.startsWith("car")); // true
        System.out.println(trie.startsWith("ora")); // false
    }
}