205. Isomorphic Strings 同构字符串

题目简述:

Given two strings s and t, determine if they are isomorphic.

Two strings are isomorphic if the characters in s can be replaced to get t.

All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character but a character may map to itself.

 

第一次作答:

class Solution:
    def isIsomorphic(self, s, t):
        """
        :type s: str
        :type t: str
        :rtype: bool
        """
        s_dict = {}
        t_dict = {}
        tmp_s = ""
        tmp_t = ""
        for tmp_c in s:
            if tmp_c in s_dict:
                s_dict[tmp_c] += 1
            else:
                s_dict[tmp_c] = 1
            tmp_s += str(s_dict[tmp_c])
        
        for tmp_c in t:
            if tmp_c in t_dict:
                t_dict[tmp_c] += 1
            else:
                t_dict[tmp_c] = 1
            tmp_t += str(t_dict[tmp_c])
        
        if tmp_s == tmp_t:
            return True
        else:
            return False

这次作答的主要问题是:只记录了每个字符出现的次数,以次数来表明是否同构,出错了“aba”和“baa”,因为显示结果都是112.

第二次作答:

class Solution:
    def isIsomorphic(self, s, t):
        """
        :type s: str
        :type t: str
        :rtype: bool
        """
        return [s.find(i) for i in s] == [t.find(j) for j in t]

通过字符串的find方法,获取到所有第i个字符出现的索引值,没有强调具体是哪个字符,但是指明了顺序

第二种方式:

class Solution:
    def isIsomorphic(self, s, t):
        """
        :type s: str
        :type t: str
        :rtype: bool
        """
        d1, d2 = {}, {}
        for i, val in enumerate(s):  # 这里可以记录一个val出现的顺序,刚才自己写的部分就忽略了这个问题
            d1[val] = d1.get(val, []) + [i]
        for i, val in enumerate(t):
            d2[val] = d2.get(val, []) + [i]
        return sorted(d1.values()) == sorted(d2.values())

下面是一个输入与输出的例子:我们记录了每个字符是什么,并且出现的位置是多少,用sorted来表示是否同构的意思,因为我们并不关注字符是否相同,只是某些字符出现的位置是否一致。

Your input
"egg"
"add"
Your stdout
{'g': [1, 2], 'e': [0]}
{'a': [0], 'd': [1, 2]}

转载于:https://www.cnblogs.com/Vancuicide/p/9596694.html

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