211. 添加与搜索单词 - 数据结构设计

211. 添加与搜索单词 - 数据结构设计

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题目链接：211. 添加与搜索单词 - 数据结构设计

代码如下：

//前缀树 参考leetcode官方题解
class TrieNode {
public:
    vector<TrieNode*> children;
    bool isEnd;
    TrieNode() : children(26), isEnd(false) {}
};

class WordDictionary {
private:
    TrieNode* trie;
    void insert(TrieNode* root, const string& word) {
        TrieNode* node = root;
        for (int i = 0; i < word.size(); i++) {
            if (node->children[word[i] - 'a'] == nullptr)
                node->children[word[i] - 'a'] = new TrieNode();
            node = node->children[word[i] - 'a'];
        }
        node->isEnd = true;
    }

    //深度遍历
    bool dfs(const string& word, int index, TrieNode* node) {
        if (index ==
            word.size()) //如果到了单词的末尾。看看前缀树是否到达单词末尾
            return node->isEnd;
        if (word[index] >= 'a' && word[index] <= 'z') { //如果是字母，就继续查找
            TrieNode* child = node->children[word[index] - 'a'];
            if (child != nullptr && dfs(word, index + 1, child))
                return true;
        } else if (word[index] ==
                   '.') { //如果是.，就把26个字母都查找一遍进行匹配
            for (int i = 0; i < 26; i++) {
                TrieNode* child = node->children[i];
                if (child && dfs(word, index + 1, child))
                    return true;
            }
        }
        return false;
    }

public:
    WordDictionary() { trie = new TrieNode(); }

    void addWord(string word) { insert(trie, word); }

    bool search(string word) { return dfs(word, 0, trie); }
};

/**
 * Your WordDictionary object will be instantiated and called as such:
 * WordDictionary* obj = new WordDictionary();
 * obj->addWord(word);
 * bool param_2 = obj->search(word);
 */