```
class Solution {
public:
bool isIsomorphic(string s, string t) {
//I think this will solved but TLE
if(s.length() != t.length()) return false;
vector<char> hash_s;
vector<char> hash_t;
hash_s.push_back(s[0]);
hash_t.push_back(t[0]);
int idx = 0;
for(int i = 1; i < s.length(); i++)
{
for(; idx < hash_s.size(); idx++)
{
if((hash_s[idx] == s[i] && hash_t[idx] != t[i]) || (hash_t[idx] == t[i] && hash_s[idx] != s[i]))
return false;
}
hash_s.push_back(s[i]);
hash_t.push_back(t[i]);
idx = 0;
}
return true;
}
};
```

I have tried some simple case...I think the answer is correct but TLE in one case.

Can some one fix it?

The idea is push first element into array, then check the hash table (vector). if not pass the return false.

I guess the drawback is, when a input string is large. it needs N^2 time to search.