leetcode 205: Isomorphic Strings

Use two maps to save the relationships from s[i] to t[i] and from t[i] to s[i]. Make sure there is no duplicate.

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        unordered_map<char,char> mpfrom,mpto;
        for(int i=0;i<s.size();i++)
        {
            if(mpfrom.find(s[i])==mpfrom.end()&&mpto.find(t[i])==mpto.end())
            {
                mpfrom.insert(make_pair(s[i],t[i]));
                mpto.insert(make_pair(t[i],s[i]));
            }
            else if(mpfrom.find(s[i])!=mpfrom.end()&&mpfrom[s[i]]!=t[i])
                return false;
            else if(mpto.find(t[i])!=mpto.end()&&mpto[t[i]]!=s[i])
                return false;
        }
        return true;
    }
};