```
class Solution(object):
def isIsomorphic(self, s, t):
"""
:type s: str
:type t: str
:rtype: bool
"""
# map the s -> t and t -> s, make sure it has one to one mapping realationship
if len(s) != len(t):
return False
charMap1 = {}
charMap2 = {}
for i in range(len(s)):
if s[i] not in charMap1 and t[i] not in charMap2:
charMap1[s[i]] = t[i]
charMap2[t[i]] = s[i]
elif s[i] in charMap1 and t[i] in charMap2:
if charMap1[s[i]] != t[i] or charMap2[t[i]] != s[i]:
return False
else:
return False
return True
```