【python】205. Isomorphic Strings

class Solution(object):
    def isIsomorphic(self, s, t):
        """
        :type s: str
        :type t: str
        :rtype: bool
        """
        l = len(s)
        print(l)
        #两次遍历
        a = {}        
        for i in range(l):#从0到l
            if s[i] not in a:
                a[s[i]] = t[i]
            else:
                if a[s[i]] is not t[i]:
                    return False
        b = {}
        for i in range(l):#从0到l
            if t[i] not in b:
                b[t[i]] = s[i]
            else:
                if b[t[i]] is not s[i]:
                    return False        
        return True