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.
判断两个字符串是否同构，即每个字母满足对应的单射关系。
两个mp维护映射关系就可以了。
代码语言：javascript复制class Solution {
public:
bool isIsomorphic(string s, string t) {
unordered_map<char, char> mp, mp2;
for(int i = 0; i < s.size(); i )
{
if(mp.find(s[i]) != mp.end())
{
if(mp[s[i]] != t[i]) return false;
}
else
mp[s[i]] = t[i];
if(mp2.find(t[i]) != mp2.end())
{
if(mp2[t[i]] != s[i]) return false;
}
else
mp2[t[i]] = s[i];
}
return true;
}
};
