LeetCode OJ：Isomorphic Strings（同构字符串）

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.

看两个字符串是否同构,用map就可以解决，不过要注意双向都要检查，代码如下：

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        map<char, char> m1;
        map<char, char> m2;
        if(s.size() != t.size())
            return false;
        for(int i = 0; i < s.size(); ++i){
            if(m1.find(s[i]) == m1.end() && m2.find(t[i]) == m2.end()){
                m1[s[i]] = t[i];
                m2[t[i]] = s[i];
            }
            else if(m1.find(s[i]) != m1.end() && m2.find(t[i]) != m2.end()){
                if(m1[s[i]] != t[i] || m2[t[i]] != s[i])
                    return false;
            }else{
                return false;
            }
        }
        return true;
    }
};