双映射问题

前言

双射说明两个映射表互为映射关系，正反都可推

代码

bool isIsomorphic(string s, string t) 
{
    map<char, char> t2s, s2t;
    for (int i = 0; i < s.size(); i++) 
    {
         char a = s[i], b = t[i];
         if (s2t.contains(a) && s2t[a] != b || t2s.contains(b) && t2s[b] != a)
                return false;
      
         s2t[a] = b;
         t2s[b] = a;
    }
    return true;
}