Isomorphic String

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.

Analyse:

1. map twice.

Runtime: 68ms.

class Solution {
public:
bool isIsomorphic(string s, string t) {
if(s.length() == 0) return true;

map<char, char> m;
m[s[0]] = t[0];
map<char, char> n;
n[t[0]] = s[0];
for(int i = 1; i < s.length(); i++){
if(m.find(s[i]) != m.end() && m.find(s[i])->second != t[i] ||
n.find(t[i]) != n.end() && n.find(t[i])->second != s[i]) return false;
else{
m.insert(pair<char, char> (s[i], t[i]));
n.insert(pair<char, char> (t[i], s[i]));
}
}
return true;
}
};

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