This is my CPP solution.
class Solution {
public:
bool isIsomorphic(string s, string t) {
vector<int> s_map(128,0);
vector<int> t_map(128,0);
int n = s.size(), m = t.size();
if(n != m)
return false;
for(int i=0;i<n;i++){
if(s_map[s[i]]!=t_map[t[i]])
return false;
else if(!(s_map[s[i]] || t_map[t[i]])){
s_map[s[i]] = i+1;
t_map[t[i]] = i+1;
}
}
return true;
}
};