Isomorphic Strings.

isomorphic.cpp

/*
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.
*/

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        if (s.size() != t.size()) {
            return false;
        }
        
        map<char,char> strMap;
        map<char,int> alreadyMapped;
        
        for (int i=0; i<t.size(); i++) {
            if(strMap[s[i]]) {
                if (strMap[s[i]] == t[i]) {
                    continue;
                } else {
                    return false;
                }
            } else {
                if (alreadyMapped[t[i]]) {
                    return false;
                }
                strMap[s[i]] = t[i];
                alreadyMapped[t[i]] = 1;
            }
        }
        return true;
    }
};