[leetcode]Isomorphic Strings

题目来源：https://leetcode.com/problems/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.

Note:
You may assume both s and t have the same length.

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        map<int,int> mapst, mapts;
		int len = s.size(), sc, tc;
        for(int i=0; i<len; i++) {
            sc = s[i]-'a'+1;
            tc = t[i]-'a'+1;
            if(mapst[sc]==0) mapst[sc] = tc;
            if(mapts[tc]==0) mapts[tc] = sc;
            if(mapst[sc]!=tc || mapts[tc]!=sc) {
                return false;
            }
        }
        return true;
    }
};