leetcode之Isomorphic Strings

这题跟word pattern有点像，不过要是用word pattern的替换法来做的话肯定会超时的，这题的替换仅仅是单个字符对单个字符。所以用别的方法来看。代码如下：

class Solution(object):
    def isIsomorphic(self, s, t):
        """
        :type s: str
        :type t: str
        :rtype: bool
        """
        dict1 = {}
        if len(s) == 0:
            if len(t) == 0:
                return True
            else:
                return False
        else:
            if len(t) == 0:
                return False
        if len(s) != len(t):
            return False
        for i in range(len(s)):
            if s[i] not in dict1.keys():
                dict1[s[i]] = t[i]
            else:
                if t[i] != dict1[s[i]]:
                    return False
        else:
            set1 = set(dict1.values())
            if len(set1) == len(dict1.values()):
                return True
            else:
                return False