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) {

int m = s.size();

int n = t.size();

if(m != n)

return false;

unordered_map<char, char> m1; //s --> t

unordered_map<char, char> m2; //t --> s

for(int i = 0; i < m; i ++)

{

char schar = s[i];

char tchar = t[i];

// the same char in s map to different chars in t

if(m1.find(schar) != m1.end() && m1[schar] != tchar)

return false;

// two different chars in s map tp the same char in t

if(m2.find(tchar) != m2.end() && m2[tchar] != schar)

return false;

m1[schar] = tchar;

m2[tchar] = schar;

}

return true;

}

};

• C++的标准库操作还是不熟练