LeetCode 205. Isomorphic Strings 双map ***

一、题目

Given two strings s and t, determine if they are isomorphic.

Two strings are isomorphic if the characters in s can be replaced to gett.

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.

题意：给定两个字符串s和t，看他们之间是否构成同构。所谓同构就是s串通过某种映射能够转化为t串，按照字符原样顺序替换，一看例子就明白。

注意：字符串的题，字符集范围，为空的时候返回什么，大小写够成同构吗？

         两个字符不能同时映射到一个字符上，一个字符可以映射到它本身。

思路：

        做了209来做205就轻松很多了。两个map，一个以s为键t为值，一个以t为键s为值。当两者之间都没有相应的映射关系时，加载映射关系。当其中之一有映射关系，看其映射是否和历史映射保持一致，否则就返回false。

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