Design a data structure that supports adding new words and finding if a string matches any previously added string.

Implement the WordDictionary class:

• WordDictionary() Initializes the object.
• void addWord(word) Adds word to the data structure, it can be matched later.
• bool search(word) Returns true if there is any string in the data structure that matches word or false otherwise. word may contain dots '.' where dots can be matched with any letter.

Example

Input
["WordDictionary","addWord","addWord","addWord","search","search","search","search"]
[[],["bad"],["dad"],["mad"],["pad"],["bad"],[".ad"],["b.."]]
Output
[null,null,null,null,false,true,true,true]

Explanation
WordDictionary wordDictionary = new WordDictionary();
wordDictionary.addWord("bad");
wordDictionary.addWord("dad");
wordDictionary.addWord("mad");
wordDictionary.search("pad"); // return False
wordDictionary.search("bad"); // return True
wordDictionary.search(".ad"); // return True
wordDictionary.search("b.."); // return True

Solution

var WordDictionary = function () {
  //Declare a root node
  this.n = {};
  this.isWord = false;
  return this;
};

/**
 * @param {string} word
 * @return {void}
 */
WordDictionary.prototype.addWord = function (word) {
  //Declare a current node
  let curr = this;
  //Loop through the word
  for (let i = 0; i < word.length; i++) {
    if (!curr.n[word[i]]) {
      //If the current node does not have the letter, add it
      curr.n[word[i]] = new WordDictionary(word[i]);
    }
    curr = curr.n[word[i]];
  }
  //Set the last node to be a word
  curr.isWord = true;
};

/**
 * @param {string} word
 * @return {boolean}
 */
WordDictionary.prototype.search = function (word, start = 0, newCurr = null) {
  let curr = this;
  //If a new current node is passed in, set it to be the current node
  if (newCurr != null) curr = newCurr;
  for (let i = start; i < word.length; i++) {
    let char = word[i];
    if (char == ".") {
      let letters = Object.keys(curr.n);
      let res = false;
      for (let letter of letters) {
        //Recursively call search on each letter
        res = res || this.search(word, i + 1, curr.n[letter]);
      }
      return res;
    } else if (!curr.n[char]) {
      return false;
    }
    //Set the current node to be the next letter
    curr = curr.n[char];
  }
  return curr.isWord;
};

/**
 * Your WordDictionary object will be instantiated and called as such:
 * var obj = new WordDictionary()
 * obj.addWord(word)
 * var param_2 = obj.search(word)
 */