leetcode trie

trie.js

/**
 * Returns an instance of Trie data structure to fill with
 * strings that can be searched through with high efficiency
 * Example usage:
 * ```
 *   const words = ['cats', 'dogs', 'racoons', 'foxes'];
 *   const t = trie();
 *   words.forEach(t.insert);
 *   t.search('cat'); // false
 *   t.search('cat', true); // true
 *   t.search('cats'); // true
 * ```
 */
const trie = () => {
  const node = (value) => ({
    value,
    isEndOfWord: false,
    children: {}
  });

  const root = node(null);

  const insert = (word) => {
    let current = root;
    for (let char of word){
      if (current.children[char] === undefined) {
          current.children[char] = node(char);
      }
      current = current.children[char];
    }
    current.isEndOfWord = true;
  }

  const search = (word, startsWith = false) => {
    let current = root;
    for (let char of word) {
      if (current.children[char] === undefined) {
          return false;
      }
      current = current.children[char];
    }
    return startsWith || current.isEndOfWord;
  }

  return {
    insert,
    search,
  };
}