problem:
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.
solution:这道题木实则判断两个字符串是否为同构字符串。只要保证s t 互相都映射成功，用unordered_map 来记录它们之间的相互映射
class Solution {
public:
bool isIsomorphic(string s, string t) {
if(s.size()!=t.size())
return false;
unordered_map<char,char> datamap;
for(int i=0;i<s.size();i++)
{
if(datamap.find(s[i])==datamap.end())
datamap[s[i]]=t[i];
else if(datamap[s[i]]!=t[i])
return false;
}
datamap.clear();
for(int i=0;i<t.size();i++)
{
if(datamap.find(t[i])==datamap.end())
datamap[t[i]]=s[i];
else if(datamap[t[i]]!=s[i])
return false;
}
}
};
原文：http://www.cnblogs.com/xiaoying1245970347/p/4612557.html