[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.

 

 1 class Solution {
 2 public:
 3     bool wordPattern(string pattern, string str) {
 4         vector<string> dic;
 5         istringstream sin(str);
 6         string tmp;
 7         while (sin >> tmp) dic.push_back(tmp);
 8         if (dic.size() != pattern.size()) return false;
 9         unordered_map<char, string> mp1;
10         unordered_map<string, char> mp2;
11         for (int i = 0; i < pattern.size(); ++i) {
12             if (mp1.find(pattern[i]) == mp1.end()) {
13                 mp1[pattern[i]] = dic[i];
14             } else if (mp1[pattern[i]] != dic[i]) {
15                 return false;
16             }
17             if (mp2.find(dic[i]) == mp2.end()) {
18                 mp2[dic[i]] = pattern[i];
19             } else if (mp2[dic[i]] != pattern[i]) {
20                 return false;
21             }
22         }
23         return true;
24     }
25 };