Isomorphic Strings leetcode 205

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.

判断两个串是不是同构串，简单地实现题

class Solution{
public:
bool isIsomorphic(string s,string t){
map<char,char> tab;
for(int i=0;i<s.length();i++){
if(tab.find(s[i])==tab.end())tab[s[i]]=t[i];
else if(tab[s[i]]!=t[i])return false;
}
tab.clear();
for(int i=0;i<s.length();i++){
if(tab.find(t[i])==tab.end())tab[t[i]]=s[i];
else if(tab[t[i]]!=s[i])return false;
}
return true;
}
};

68ms；

class Solution{
public:
bool isIsomorphic(string s,string t){
int Sm[128]={0};
int Tm[128]={0};
for(int i=0;i<s.length();i++){
if(Sm[s[i]]!=Tm[t[i]])return false;
Sm[s[i]]=i+1;
Tm[t[i]]=i+1;
}
return true;
}
};

8ms