[LeetCode] Word Pattern

Word Pattern

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

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:

1. Both pattern and str contains only lowercase alphabetical letters.
2. Both pattern and str do not have leading or trailing spaces.
3. Each word in str is separated by a single space.
4. Each letter in pattern must map to a word with length that is at least 1.

 

Credits:
Special thanks to @minglotus6 for adding this problem and creating all test cases.

 

class Solution {
public:
    bool wordPattern(string pattern, string str) {
        vector<string> dic;
        istringstream sin(str);
        string tmp;
        while (sin >> tmp) dic.push_back(tmp);
        if (dic.size() != pattern.size()) return false;
        unordered_map<char, string> mp1;
        unordered_map<string, char> mp2;
        for (int i = 0; i < pattern.size(); ++i) {
            if (mp1.find(pattern[i]) == mp1.end()) {
                mp1[pattern[i]] = dic[i];
            } else if (mp1[pattern[i]] != dic[i]) {
                return false;
            }
            if (mp2.find(dic[i]) == mp2.end()) {
                mp2[dic[i]] = pattern[i];
            } else if (mp2[dic[i]] != pattern[i]) {
                return false;
            }
        }
        return true;
    }
};