class Solution {
public:
    bool wordPattern(string pattern, string str) {
        unordered_map<char, int> patternMap;
        unordered_map<string, int> wordMap;
        istringstream iss(str);
        const int patternLen = pattern.length();
        int i = 0;

        for(string word; iss >> word; ++i) {
            if(i == patternLen || patternMap[pattern[i]] != wordMap[word]) {
                return false;
            }

            patternMap[pattern[i]] = wordMap[word] = i+1;
        }

        return i == patternLen;
    }
};