【刷题-LeetCode】205. Isomorphic Strings

205. 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.

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

解 确保s->t和t->s都是单射（一一映射），用两个map分别表示正向和反向的映射关系

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        if(s.size() != t.size())return false;
        unordered_map<char, char>mp1, mp2;
        for(int i = 0; i < s.size(); ++i){
            if(mp1[t[i]] && mp1[t[i]] != s[i])return false;
            if(mp2[s[i]] && mp2[s[i]] != t[i])return false;
            mp1[t[i]] = s[i];
            mp2[s[i]] = t[i];
        }
        return true;
    }
};