Leetcode 205. isomorphic string (2022.07.24)

Given two strings s and t , Judge whether they are isomorphic .

If s The characters in can be replaced according to some mapping relationship t , So these two strings are isomorphic .

Every character that appears should be mapped to another character , Without changing the order of characters . Different characters cannot be mapped to the same character , The same character can only be mapped to the same character , Characters can be mapped to themselves .

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

Tips ：

1 <= s.length <= 5 * 104
t.length == s.length
s and t By any valid ASCII Character composition

source ： Power button （LeetCode）
link ：https://leetcode.cn/problems/isomorphic-strings

Method 1 ： Hashtable

C++ Submission ：

class Solution {
    
public:
    bool isIsomorphic(string s, string t) {
    
        unordered_map<char, char> s2t;
        unordered_map<char, char> t2s;
        int len = s.length();
        for (int i = 0; i < len; ++i) {
    
            char x = s[i], y = t[i];
            if ((s2t.count(x) && s2t[x] != y) || (t2s.count(y) && t2s[y] != x)) {
    
                return false;
            }
            s2t[x] = y;
            t2s[y] = x;
        }
        return true;
    }
};