LeetCode OJ：Isomorphic Strings（同构字符串）

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.

看两个字符串是否同构,用map就可以解决，不过要注意双向都要检查，代码如下：

 1 class Solution {
 2 public:
 3     bool isIsomorphic(string s, string t) {
 4         map<char, char> m1;
 5         map<char, char> m2;
 6         if(s.size() != t.size())
 7             return false;
 8         for(int i = 0; i < s.size(); ++i){
 9             if(m1.find(s[i]) == m1.end() && m2.find(t[i]) == m2.end()){
10                 m1[s[i]] = t[i];
11                 m2[t[i]] = s[i];
12             }
13             else if(m1.find(s[i]) != m1.end() && m2.find(t[i]) != m2.end()){
14                 if(m1[s[i]] != t[i] || m2[t[i]] != s[i])
15                     return false;
16             }else{
17                 return false;
18             }
19         }
20         return true;
21     }
22 };