Trie

package backToBasics;

import java.util.HashMap;
import java.util.Map;

public class MyTrie {

    private TrieNode mRootTrieNode;

    MyTrie() {
        mRootTrieNode = new TrieNode();
    }

    public void insertWord(String word) {
        insertWord(0, word, mRootTrieNode);
    }

    private void insertWord(int i, String word, TrieNode currentNode) {
        if (i == word.length()) {
            currentNode.endOfWord = true;
            return;
        }

        if (currentNode.characterMap.containsKey(word.charAt(i))) {
            currentNode = currentNode.characterMap.get(word.charAt(i));
        } else {
            TrieNode node = new TrieNode();
            currentNode.characterMap.put(word.charAt(i), node);
            currentNode = node;
        }
        i++;
        insertWord(i, word, currentNode);
    }


    public boolean contains(String word) {
        return contains(0, mRootTrieNode, word);
    }

    private boolean contains(int i, TrieNode node, String word) {
        if (i == word.length()) {
            return node.endOfWord;
        }
        if (node.characterMap.containsKey(word.charAt(i))) {
            node = node.characterMap.get(word.charAt(i));
            i++;
            return contains(i, node, word);
        } else {
            return false;
        }
    }


    public boolean deleteWord(String word) {
        return delete(0, mRootTrieNode, word);
    }

    private boolean delete(int i, TrieNode node, String word) {
        if (i == word.length()) {
            if (!node.endOfWord) {
                return false;
            }

            node.endOfWord = false;

            return node.characterMap.size() == 0;
        }
        if (node.characterMap.containsKey(word.charAt(i))) {
            node = node.characterMap.get(word.charAt(i));
            i++;
            if (delete(i, node, word)) {
                node.characterMap.remove(word.charAt(i - 1));
                return node.characterMap.size() == 0;
            }
        } else {
            //word does not exist
            return false;
        }
        return false;
    }


    class TrieNode {
        Map<Character, TrieNode> characterMap = new HashMap<>();
        boolean endOfWord = false;
    }

    public static void main(String args[]) {
        MyTrie myTrie = new MyTrie();

        myTrie.insertWord("abc");
        myTrie.insertWord("abg");
        myTrie.insertWord("saldi");
        myTrie.insertWord("abgd");
        System.out.println(myTrie.contains("saldi"));
        System.out.println(myTrie.contains("abg"));
        myTrie.deleteWord("abg");
        System.out.println(myTrie.contains("abg"));
        System.out.println(myTrie.contains("saldi"));
        myTrie.deleteWord("saldi");
        System.out.println(myTrie.contains("saldi"));
    }
}