Leetcode 205. Isomorphic Strings

原题：
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.
解决方法：
用两个哈希表来保存各种的对应关系，对每一个字母进行检查，如果不匹配，返回false,否则返回true。

代码：

bool isIsomorphic(string s, string t) {
if (s.size() != t.size())
return false;
int n = s.size();
unordered_map<char, char> ms, mt;
for(int i = 0; i < n; i++){
if (!ms.count(s[i]) && !mt.count(t[i]) ){
ms[s[i]] = t[i];
mt[t[i]] = s[i];
}else if (!ms.count(s[i]) || !mt.count(t[i])){
return false;
}else{
if (ms[s[i]] != t[i] || mt[t[i]] != s[i])
return false;
}
}

return true;
}