LeetCode OJ：Add and Search Word - Data structure design（增加以及搜索单词）

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 letters a-z or .. A . means it can represent any one letter.

For example:

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

这题用set做的话可能会超时，应该自己定义数据结构，构造一个单词数，这样效率更高，在搜索的时候就是dfs了， 代码如下：

 class WordDictionary {
 public:
     struct TreeNode{
     public:
         TreeNode *child[];
         bool isWord;

         TreeNode() : isWord(false){
             for(auto & a : child)
                 a = NULL;
         }
     };

     WordDictionary() {
         root = new TreeNode();
     }

     // Adds a word into the data structure.
     void addWord(string word) {
         TreeNode * p = root;
         for(auto & a : word){
             if(!p->child[a-'a'])
                 p->child[a-'a'] = new TreeNode;
             p = p->child[a-'a'];
         }
         p->isWord = true;//标记一个单词
     }

     bool searchWord(string & word, TreeNode * p, int index)
     {
         if(word.size() == index) return p->isWord;//这条很关键
         if(word[index] == '.'){
             for(auto & a : p->child){
                 if(a && searchWord(word, a, index+)) return true;
             }
             return false;//不要忘了
         }else{
             return (p->child[word[index] - 'a'])&&searchWord(word, p->child[word[index] - 'a'], index+);
         }
     }

     bool search(string word) {
         return searchWord(word, root, );
     }

     // WordDictionary()//进入函数后会首先执行构造函数
     // : root(new TreeNode) {}
 private:
     TreeNode * root;
 };

这回写的比较乱，见谅