LeetCode 211.Add and Search Word - Data structure design(trie树)

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题意:创建一个单词库,支持两种操作,给库里面加入新单词和查询某单词是否在库中,但是注意用’.’来做通配符,可以代替任意字符.
分析:trie树的改造.主要是通配符的处理.这里把搜索函数处理了一下,用递归实现,当配件通配符号的时候遍历它的所有26个分枝来求满足条件的.

code:

class WordDictionary {private:    struct node {        int have;        node *next[26];        node(void) {            have = 0;            for (int i = 0; i < 26; i++) next[i] = NULL;        }    };public:    node *root = new node;    // Adds a word into the data structure.    // The time consumer is O(n)    void addWord(string word) {        node *p = root;        for (int i = 0; i < word.size(); i++) {            int aim = word[i] - 'a';            if ((p -> next)[aim] == NULL) (p -> next)[aim] = new node;            p = (p -> next)[aim];        }        (p -> have) = (p -> have) + 1;    }    bool can(node *p, int head, const string &word) {        if (head == word.size() && p -> have) return true;        int aim = word[head] == '.' ? 26 : word[head] - 'a';        if (aim == 26) {            for (int i = 0; i < 26; i++)                if ((p -> next)[i] != NULL && can( (p -> next)[i], head + 1, word)) return true;            return false;        }        if ((p -> next)[aim] != NULL)            return can((p -> next)[aim], head + 1, word);        return false;    }    // Returns if the word is in the data structure. A word could    // contain the dot character '.' to represent any one letter.    bool search(string word) {        node *p = root;        int head = 0;        return can(p, head, word);    }};// Your WordDictionary object will be instantiated and called as such:// WordDictionary wordDictionary;// wordDictionary.addWord("word");// wordDictionary.search("pattern");