LeetCode205. Isomorphic Strings

一、题目

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

Two strings s and t 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

Constraints:

1 <= s.length <= 5 * 104
t.length == s.length
s and t consist of any valid ascii character.

二、题解

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        int n = s.size();
        unordered_map<char,char> map1;
        unordered_map<char,char> map2;
        for(int i = 0;i < n;i++){
            //如果在map1中不存在
            if(map1.find(s[i]) == map1.end()) map1[s[i]] = t[i];
            else{
                if(map1[s[i]] != t[i]) return false;
            }
            //如果映射在map2中不存在
            if(map2.find(t[i]) == map2.end()) map2[t[i]] = s[i];
            else{
                if(map2[t[i]] != s[i]) return false;
            }
        }
        return true;
    }
};