[leetcode]205. Isomorphic Strings

题目链接：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.

class Solution {  
public:  
     string transferStr(string s){  
        char table[128] = {0};  
        char tmp = '0';  
        for (int i=0; i<s.length(); i++) {  
            char c = s.at(i);  
            if (table[c] == 0) {  
                table[c] = tmp++;  
            }  
            s[i] = table[c];  
        }  
        return s;  
    }  
    bool isIsomorphic(string s, string t) {  
          
        if (s.length() != t.length()) {  
            return false;  
        }  
        if (transferStr(s) == transferStr(t)) {  
            return true;  
        }  
        return false;  
    }  
};