LeetCode_Isomorphic Strings

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Isomorphic Strings

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.
（判断是否为同构字符串）

Example:



1. 哈希表

用哈希表保存相同字符的index。具体实现过程如下：

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from collections import defaultdict 

class Solution:
    def isIsomorphic(self, s: str, t: str) -> bool:
        if not s:
            return True
        
        map_s, map_t = defaultdict(list), defaultdict(list)
        
        for i in range(len(s)):
            map_s[s[i]].append(i)
            map_t[t[i]].append(i)
            
            if map_s[s[i]] != map_t[t[i]]:
                return False

        return True

2. zip & 集合

首先判断组成两个字符串的字符的数目是否相同，然后使用 zip 函数判断字符串相同位置的字符组合是否相同。具体实现过程如下：

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class Solution:
    def isIsomorphic(self, s: str, t: str) -> bool:
        if(len(set(zip(s,t)))==len(set(s))==len(set(t))): 
        	return True
        else: 
        	return False