Lintcode 单词的添加与查找

 单词的添加与查找

•  描述
•  笔记
•  数据
•  评测

设计一个包含下面两个操作的数据结构：addWord(word), search(word)

addWord(word)会在数据结构中添加一个单词。而search(word)则支持普通的单词查询或是只包含.和a-z的简易正则表达式的查询。

一个 . 可以代表一个任何的字母。

您在真实的面试中是否遇到过这个题？ 

Yes

 注意事项

你可以假设所有的单词都只包含小写字母 a-z。

样例

addWord("bad")addWord("dad")addWord("mad")search("pad")  // return falsesearch("bad")  // return truesearch(".ad")  // return truesearch("b..")  // return true

AC代码如下：

struct trieNode {        trieNode() : terminableSize(0) {            for (int i = 0; i < 26; ++i) {                children[i] = NULL;            }        }                ~trieNode() {            for (int i = 0; i < 26; ++i) {                if (children[i]) {                    delete children[i];                    children[i] = NULL;                }            }        }                int terminableSize;        trieNode *children[26];};class WordDictionary {public:    WordDictionary() : root(new trieNode) {}        size_t Index(char c) {        return static_cast<size_t>(c % 26);    }        // Adds a word into the data structure.    void addWord(string word) {        // Write your code here        trieNode *cur = root;        for (size_t i = 0; i < word.size(); ++i) {            size_t idx = Index(word[i]);            if (!cur->children[idx]) {                cur->children[idx] = new trieNode;            }            cur = cur->children[idx];        }        ++cur->terminableSize;    }    // 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) {        return search_dfs(word, root);    }        bool search_dfs(string word, trieNode *cur) {        if (word.size() == 0 && cur->terminableSize > 0)            return true;        for (size_t i = 0; i < word.size(); ++i) {            if (word[i] == '.') {                for (size_t j = 0; j < 26; ++j) {                    if (cur->children[j] && search_dfs(word.substr(i + 1), cur->children[j]))                        return true;                }                return false;            }            else {                size_t idx = Index(word[i]);                if (!cur->children[idx])                    return false;                cur = cur->children[idx];            }        }        if (cur->terminableSize > 0)            return true;        return false;    }    private:        trieNode *root;};// Your WordDictionary object will be instantiated and called as such:// WordDictionary wordDictionary;// wordDictionary.addWord("word");// wordDictionary.search("pattern");