Implement Magic Dictionary

class MagicDictionary { public: class TrieNode { public: TrieNode() : isWord(false) {} unordered_map child; bool isWord; };

/** Initialize your data structure here. */
MagicDictionary() {
    root = new TrieNode();
}

/** Build a dictionary through a list of words */
void buildDict(vector<string> dict) {
    for (auto word: dict) {
        insertWord(word);
    }
}

/** Returns if there is any word in the trie that equals to the given word after modifying exactly one character */
bool search(string word) {
    return searchWord(root, 0, 0, word);
}

void insertWord(string word) {
    TrieNode *cur = root;
    for (auto ch: word) {
        if (!cur->child[ch]) {
            cur->child[ch] = new TrieNode();
        }
        cur = cur->child[ch];
    }
    cur->isWord = true;
}

bool searchWord(TrieNode *root, int start, int diff, string& word) {
    if (start == word.size()) return diff == 1 && root->isWord;
    if (root->child.count(word[start])) {
        if (searchWord(root->child[word[start]], start+1, diff, word)) return true;

    }

    for (auto it: root->child) {
        if (it.first == word[start]) continue;
        if (searchWord(it.second, start+1, diff+1, word)) return true;
    }
    return false;
}

private: TrieNode *root; };