[LeetCode] Word Pattern

This problem can be solved in very neat codes (yeah, you will see Stefan posting many nice solutions).

The solution in the above link is so nice that I can almost do nothing to improve it instead of using unordered_map -_-

class Solution {
public:
    bool wordPattern(string pattern, string str) {
        unordered_map<char, int> p2i;
        unordered_map<string, int> w2i;
        istringstream in(str);
        int i = 0, n = pattern.length();
        for (string word; in >> word; i++) {
            if (i >= n || p2i[pattern[i]] != w2i[word])
                return false;
            p2i[pattern[i]] = w2i[word] = i + 1;
        }
        return i == n;
    }
};

If you wonder why it uses i + 1 instead of simply using i as the values, I mention it at the first comment in the above link :-)