leetcode 205

205. 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.

设定两个字符串长度相等，所谓的“同构”，就是字符串 s 中的字符可以一对一的映射到字符串 t 中的字符。不能一对多，也不能多对一。

利用两个map实现。

代码如下：

 class Solution {
 public:
     bool isIsomorphic(string s, string t) {
         map<char, char> mapA;
         map<char, char> mapB;
         int n = s.length();
         for(int i = ; i < n; i++)
         {
             char ss = s[i];
             char tt = t[i];
             map<char, char>::iterator it = mapA.find(ss);
             if(it != mapA.end())
             {
                 if(mapA[ss] != tt)
                 {
                     return false;
                 }
             }
             else
             {
                 map<char, char>::iterator ii = mapB.find(tt);
                 if(ii != mapB.end() && mapB[tt] != ss)
                 {
                     return false;
                 }
                 else
                 {
                     mapA[ss] = tt;
                     mapB[tt] = ss;
                 }
             }
         }
         return true;
     }
 };