Implement a trie with insert, search, and startsWith methods.Example:Trie trie = new Trie();trie.insert(“apple”);trie.search(“apple”); // returns truetrie.search(“app”); // returns falsetrie.startsWith(“app”); // returns truetrie.insert(“app”); trie.search(“app”); // returns trueNote:You may assume that all inputs are consist of lowercase letters a-z.All inputs are guaranteed to be non-empty strings.难度：medium题目：实现Trie树（字典树），插入，搜索和前缀方法。你可以假定所有的输入都是小写字母，所有输入都是非空(not empty)字符串。Runtime: 89 ms, faster than 98.80% of Java online submissions for Implement Trie (Prefix Tree).class Trie { private TrieNode root; /** Initialize your data structure here. / public Trie() { root = new TrieNode(); } /* Inserts a word into the trie. / public void insert(String word) { char c = word.charAt(0); int i = 0, idx = 0; TrieNode ptr = root; for (; i < word.length(); i++, ptr = ptr.next[idx]) { idx = word.charAt(i) - ‘a’; if (null == ptr.next[idx]) { ptr.next[idx] = new TrieNode(); } } ptr.isWord = true; } /* Returns if the word is in the trie. / public boolean search(String word) { char c = word.charAt(0); int i = 0, idx = 0; TrieNode ptr = root; for (; i < word.length() - 1; i++, ptr = ptr.next[idx]) { idx = word.charAt(i) - ‘a’; if (null == ptr.next[idx]) { return false; } } TrieNode end = ptr.next[word.charAt(i) - ‘a’]; return end != null && end.isWord; } /* Returns if there is any word in the trie that starts with the given prefix. / public boolean startsWith(String prefix) { int idx = 0, i = 0; TrieNode ptr = root; for (; i < prefix.length(); i++, ptr = ptr.next[idx]) { idx = prefix.charAt(i) - ‘a’; if (null == ptr.next[idx]) { return false; } } return i >= prefix.length(); } public static class TrieNode { public boolean isWord; public TrieNode[] next = new TrieNode[26]; }}/* * Your Trie object will be instantiated and called as such: * Trie obj = new Trie(); * obj.insert(word); * boolean param_2 = obj.search(word); * boolean param_3 = obj.startsWith(prefix); */