[Leetcode]205. Isomorphic Strings

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