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:

pattern = 

"abba"

, str = 

"dog
cat cat dog"

 should return true.
pattern = 

"abba"

, str = 

"dog
cat cat fish"

 should return false.
pattern = 

"aaaa"

, str = 

"dog
cat cat dog"

 should return false.
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.

跟205. Isomorphic Strings（重要）类似

class Solution {
public:
bool wordPattern(string pattern, string str) {
int lenP = pattern.size();

vector<string> vec;
stringstream ss(str);
string s;
while (ss >> s){
vec.push_back(s);
}

int lenStr = vec.size();
if (lenP != lenStr){
return false;
}

unordered_map<string, string> hash, reflect;
for (int i = 0; i < lenP; i++){
if (!hash.count(to_string(pattern[i])) && !reflect.count(vec[i])){
hash[to_string(pattern[i])] = vec[i];
reflect[vec[i]] = to_string(pattern[i]);
}
else{
if (hash[to_string(pattern[i])] != vec[i]){
return false;
}
}
}
return true;
}
};