211. Add and Search Word - Data structure design

Design a data structure that supports the following two operations:

void addWord(word)
bool search(word)

search(word) can search a literal word or a regular expression string containing only lettersa-zor.. A.means it can represent any one letter.

Example:

addWord("bad")
addWord("dad")
addWord("mad")
search("pad") ->false
search("bad") ->true
search(".ad") ->true
search("b..") ->true

FB follow up: process "*"

Thoughts:

1. Trie Tree excercise

class WordDictionary {

    private TrieNode root; 

    /** Initialize your data structure here. */
    public WordDictionary() {
        root = new TrieNode();
    }

    /** Adds a word into the data structure. */
    public void addWord(String word) {
        TrieNode node = root;
        for (char c: word.toCharArray()){
            if(node.children[c - 'a'] == null){
                node.children[c - 'a'] = new TrieNode();
            }
            node = node.children[c - 'a'];
        }
        node.val = word;
    }

    /** Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter. */
    public boolean search(String word) {
        return match(word, 0, root);
    }

    private boolean match(String word, int depth, TrieNode node){
        if(depth == word.length()) return !node.val.equals("");
        if(word.charAt(depth) != '.'){
            return (node.children[word.charAt(depth) - 'a'] != null && match(word, depth + 1, node.children[word.charAt(depth) - 'a'] ));
        }
        else{
            for (int i = 0; i < node.children.length; i++){
                if(node.children[i] != null && match(word, depth + 1, node.children[i]))
                    return true;
            }
        }
        return false;
    }
}
class TrieNode{
        public TrieNode [] children = new TrieNode[26];
        public String val = "";
    }
/**
 * Your WordDictionary object will be instantiated and called as such:
 * WordDictionary obj = new WordDictionary();
 * obj.addWord(word);
 * boolean param_2 = obj.search(word);
 */

Python

class WordDictionary(object):

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.root = TrieNode()


    def addWord(self, word):
        """
        Adds a word into the data structure.
        :type word: str
        :rtype: void
        """
        node = self.root
        for s in word:
            if s not in node.child:
                node.child[s] = TrieNode()
            node = node.child[s]
        node.val = word

    def search(self, word):
        """
        Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter.
        :type word: str
        :rtype: bool
        """
        def match(word, depth, node):
            if depth == len(word): return not (node.val=='')
            if word[depth] != '.':
                return word[depth] in node.child and match(word, depth + 1, node.child[word[depth]])
            else:
                for c in node.child:
                    if match(word, depth+1, node.child[c]):
                        return True
            return False
        return match(word, 0, self.root)

class TrieNode(object):
    def __init__(self):
        self.child = {}
        self.val = ""


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

Python: length based dictionary: psudu- O(1) - O(n)-> for char level: O(len(char in table entry))

class WordDictionary(object):
    def __init__(self):
        self.word_dict = collections.defaultdict(list)


    def addWord(self, word):
        if word:
            self.word_dict[len(word)].append(word)

    def search(self, word):
        if not word:
            return False
        if '.' not in word:
            return word in self.word_dict[len(word)]
        for v in self.word_dict[len(word)]:
            # match xx.xx.x with yyyyyyy
            for i, ch in enumerate(word):
                if ch != v[i] and ch != '.':
                    break
            else: # if no break in previous for loop;
                return True
        return False

Python: best Trie Implementation: T: O(len(total words)); S: O(len(total words))

class WordDictionary(object):

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.root = TrieNode()


    def addWord(self, word):
        """
        Adds a word into the data structure.
        :type word: str
        :rtype: void
        """
        node = self.root
        for s in word:
            if s not in node.child:
                node.child[s] = TrieNode()
            node = node.child[s]
        node.val = True

    def search(self, word):
        """
        Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter.
        :type word: str
        :rtype: bool
        """
        def match(word, node):
            for i, c in enumerate(word):
                if c == '.':
                    for s in node.child:
                        if match(word[i + 1:], node.child[s]):
                            return True
                    return False #!
                elif c not in node.child:
                    return False
                node = node.child[c]
            return node.val

        return match(word, self.root)

class TrieNode(object):
    def __init__(self):
        self.child = {}
        self.val = False


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