100DaysofCode/Day66.java at main · justlikebing/100DaysofCode · GitHub

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class TrieNode {
    TrieNode[] children;
    boolean isEndOfWord;

    public TrieNode() {
        children = new TrieNode[26];
        isEndOfWord = false;
    }
}

class Trie {
    TrieNode root;

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

    public void insert(String word) {
        TrieNode node = root;
        for (char ch : word.toCharArray()) {
            int index = ch - 'a';
            if (node.children[index] == null) {
                node.children[index] = new TrieNode();
            }
            node = node.children[index];
        }
        node.isEndOfWord = true;
    }

    public boolean search(String word) {
        TrieNode node = root;
        for (char ch : word.toCharArray()) {
            int index = ch - 'a';
            if (node.children[index] == null) {
                return false;
            }
            node = node.children[index];
        }
        return node != null && node.isEndOfWord;
    }

    public boolean startsWith(String prefix) {
        TrieNode node = root;
        for (char ch : prefix.toCharArray()) {
            int index = ch - 'a';
            if (node.children[index] == null) {
                return false;
            }
            node = node.children[index];
        }
        return true;
    }
}

public class Main {
    public static void main(String[] args) {
        Trie trie = new Trie();
        trie.insert("apple");

        System.out.println(trie.search("apple")); // Output: true
        System.out.println(trie.search("app"));   // Output: false

        System.out.println(trie.startsWith("app")); // Output: true
    }
}