205. Isomorphic Strings [easy] Python3 C++

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.

Example 1:

Input: s = "egg", t = "add" Output: true

Example 2:

Input: s = "foo", t = "bar" Output: false

Example 3:

Input: s = "paper", t = "title" Output: true

Note:

You may assume both s and t have the same length.

题目要求：判断两个字符串的模式相同，及用一个字符串中的字符替换相同位置的第二个字符串中的字符，得到的字符串与第一个字符串相同。

Python3

class Solution: def isIsomorphic(self, s, t): """ :type s: str :type t: str :rtype: bool """ hashmap = {} for i in range(len(s)): if s[i] not in hashmap: hashmap[s[i]] = t[i] elif hashmap[s[i]] != t[i]: return False val = [hashmap[i] for i in hashmap] return len(val) == len(set(val))

C++(AC里看到的，比较巧妙)

class Solution { public: bool isIsomorphic(string s, string t) { vector<int> v1(256, -1), v2(256, -1); for(int i=0; i<s.size(); ++i) { if(v1[s[i]] != v2[t[i]]) return false; v1[s[i]] = v2[t[i]] = i; } return true; } };