Add and Search Word - Data Structure Design

 1 class TrieNode{
 2 public:
 3     TrieNode* childNode[27];
 4     bool isVal;
 5     TrieNode(){
 6         isVal = false;
 7         for(int i = 0; i < 27; i++) 
 8             childNode[i] = NULL;
 9     }
10 };
11 class WordDictionary {
12 private: 
13     TrieNode* root;
14 public:
15     WordDictionary(){
16         root = new TrieNode();
17     }
18     // Adds a word into the data structure.
19     void addWord(string word) {
20         TrieNode* temp = root;
21         for(int i = 0; i < word.size(); i++){
22             int index = word[i] - ‘a‘;
23             if(word[i] == ‘.‘) 
24                 index = 26;
25             else{
26                 if(temp->childNode[index] == NULL)
27                     temp->childNode[index] = new TrieNode();
28             }
29             temp = temp->childNode[index];
30         }
31         temp->isVal = true; //word has been inserted
32     }
33 
34     // Returns if the word is in the data structure. A word could
35     // contain the dot character ‘.‘ to represent any one letter.
36     bool search(string word) {
37         return levelSearch(word, root, 0);
38     }
39     
40     bool levelSearch(string& word, TrieNode* root, int index){
41         TrieNode* temp = root;
42         if(!temp) return false; //length of the word is larger than that of the strings in the trie
43         if(index >= word.size()) return temp->isVal;
44         
45         if(word[index] != ‘.‘) 
46             return levelSearch(word, temp->childNode[word[index] - ‘a‘], index + 1);
47         else{
48             for(int i = 0; i < 26; i++)
49                 if(levelSearch(word, temp->childNode[i], index + 1)) return true;
50             return false;
51         }
52     }
53 };
54 
55 // Your WordDictionary object will be instantiated and called as such:
56 // WordDictionary wordDictionary;
57 // wordDictionary.addWord("word");
58 // wordDictionary.search("pattern");