【leetcode】Isomorphic Strings

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.
思路：
用stl中map结构做一一对应，例如“aba”和“aab”，由于第一个a对应第二个的a，然后第二个a对应了b，这样就得返回false，因为没法替换。
Map的用法具体见：
http://blog.csdn.net/sunshinewave/article/details/8067862

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