[Leetcode]290. Word Pattern

Given a pattern and a string str, find if str follows the same pattern.

Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty word in str.

Examples:

1. pattern = "abba", str = "dog cat cat dog" should return true.
2. pattern = "abba", str = "dog cat cat fish" should return false.
3. pattern = "aaaa", str = "dog cat cat dog" should return false.
4. pattern = "abba", str = "dog dog dog dog" should return false.

Notes:
You may assume pattern contains only lowercase letters, and str contains lowercase letters separated by a single space.

class Solution {public:    bool wordPattern(string pattern, string str) {        stringstream ss(str);        string s;        vector<string> vec;        while(ss >> s)             vec.push_back(s);        if(vec.size() != pattern.size())            return false;        map<char, string> m;        int i = 0;        for(auto c : pattern)        {            if(m.count(c))            {                if(m[c] != vec[i])                    return false;            }            else            {                for(auto p : m)                {                    if(p.second == vec[i])                        return false;                }                m[c] = vec[i];            }            ++i;        }        return true;    }};