【LeetCode】205

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 "foo", "app"; returns true we can map f -> a and o->p
given "bar", "foo"; returns false we can't map both 'a' and 'r' to 'o'

given "ab", "ca"; returns true we can map 'a' -> 'b' and 'c' -> 'a'

Solution 1: one map

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        if(s.size()!=t.size())return false;
        map<char, char> m;
        for(int i=0;i<s.size();i++){
            if(!m.count(s[i])){
                map<char,char>::const_iterator iter=m.begin();
                while(iter!=m.end()){
                    if(iter->second==t[i])return false;
                    iter++;
                }
                m.insert(make_pair(s[i], t[i]));
            }else{
                if(m[s[i]]!=t[i])return false;
            }
        }
        return true;
    }
};

Solution 2: two map

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        if(s.size()!=t.size()) return false;  
        map<char,char> ms, mt;
        for(int i=0;i<s.size();i++)
        {  
            char c1=s[i], c2=t[i];  
            if(ms.count(c1)) 
                if(ms[c1]!=c2)return false;  
            if(mt.count(c2))  
                if(mt[c2]!=c1)return false;  
            ms.insert(make_pair(c1, c2));  
            mt.insert(make_pair(c2, c1));  
        }  
        return true;  
    }
};