LeetCode 205 Isomorphic Strings

Problem:

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.

For example,
Given "egg", "add", return true.

Given "foo", "bar", return false.

Given "paper", "title", return true.

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

Summary:

判断所给出的两个字符串是否为相同格式。

Solution:

解法同LeetCode 290 Word Pattern

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        int len = s.size();
        unordered_map<char, char> m;
        for (int i = 0; i < len; i++) {
            if (m.find(s[i]) == m.end()) {
                m[s[i]] = t[i];
            }
            else if (m[s[i]] != t[i]){
                return false;
            }
        }
        
        for (unordered_map<char, char>::iterator i = m.begin(); i != m.end(); i++) {
            for (unordered_map<char, char>::iterator j = m.begin(); j != m.end(); j++) {
                if (i->first != j->first && i->second == j->second) {
                    return false;
                }
            }
        }
        return true;
    }
};