890. Find and Replace Pattern

方法一：两个map
分别记录下每对char的对应关系。

class Solution {
public:
    vector<string> findAndReplacePattern(vector<string>& words, string pattern) {
        vector<string> res;
        for (auto& str : words) {
            if (match(str, pattern))
                res.push_back(str);
        }
        return res;
    }
private:
    unordered_map<char, char> m, reverseMap;
    bool match(string& str, string& pattern) {
        if (str.size() != pattern.size())
            return false;
        m.clear();
        reverseMap.clear();
        for (int i = 0; i < str.size(); ++i) {
            if (m.find(str[i]) != m.end())
                if (m[str[i]] != pattern[i])
                    return false;
            if (reverseMap.find(pattern[i]) != reverseMap.end())
                if (reverseMap[pattern[i]] != str[i])
                    return false;
            m[str[i]] = pattern[i];
            reverseMap[pattern[i]] = str[i];
        }
        return true;
    }
};

方法二：
标准化。

class Solution {
public:
    vector<string> findAndReplacePattern(vector<string>& words, string pattern) {
        string patStr = getStr(pattern);
        vector<string> res;
        for (auto word : words)
            if (patStr == getStr(word)) {
                res.push_back(word);
            }
        return res;
    }
private:
    string getStr(string word) {
        unordered_map<char, int> m;
        for (char c : word)
            if (m.find(c) == m.end())
                m[c] = m.size();
        for (int i = 0; i < word.size(); ++i)
            word[i] = 'a' + m[word[i]];
        return word;
    }
};//这个思路确实有点意思。
//标准化，将字符全用a,b,c...表示。比如mee->abb,dkd->aba，这样匹配的字符串它们的标准化字符串是一样的。