【leetcode】Isomorphic Strings

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

class Solution {
public:
bool isIsomorphic(string s, string t) {
map<char,char>mp;
for(int i=0;i<s.size();i++)
{
if(mp.find(s[i])==mp.end()) mp[s[i]]=t[i];
else if(mp[s[i]]!=t[i]) return false;
}

mp.clear();

for(int i=0;i<s.size();i++)
{
if(mp.find(t[i])==mp.end()) mp[t[i]]=s[i];
else if(mp[t[i]]!=s[i]) return false;
}

return true;
}
};