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

 1 class Solution {
 2 public:
 3     bool isIsomorphic(string s, string t) {
 4         int len = s.size();
 5         unordered_map<char, char> m;
 6         for (int i = 0; i < len; i++) {
 7             if (m.find(s[i]) == m.end()) {
 8                 m[s[i]] = t[i];
 9             }
10             else if (m[s[i]] != t[i]){
11                 return false;
12             }
13         }
14
15         for (unordered_map<char, char>::iterator i = m.begin(); i != m.end(); i++) {
16             for (unordered_map<char, char>::iterator j = m.begin(); j != m.end(); j++) {
17                 if (i->first != j->first && i->second == j->second) {
18                     return false;
19                 }
20             }
21         }
22         return true;
23     }
24 };