### 问题描述

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 "foo", "bar", return false.

Given "paper", "title", return true.

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

### 代码

class Solution {
public:
bool isIsomorphic(string s, string t) {
if(s.length()!=t.length()) return false;
char c1[256]={
'\0'
};
char c2[256]={
'\0'
};
for(int i=0;i<s.length();i++) {
if(c1[s[i]]=='\0') {
c1[s[i]] = t[i];
} else {
if(c1[s[i]]!=t[i]) {
return false;
}
}
if(c2[t[i]]=='\0') {
c2[t[i]] = s[i];
} else {
if(c2[t[i]]!=s[i]) {
return false;
}
}
}
return true;
}
};