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.
问题：给定两个字符串，判断他们是否同构。
当字符串 s 中的字符可以被替换得到另一个字符串 t , 则表示字符串 s 和 t 是同构。
import static java.lang.System.out;
import java.util.Hashtable;
public class Solution {
public boolean isIsomorphic(String s, String t) {
Hashtable<Character, Character> s_t = new Hashtable<Character, Character>();
Hashtable<Character, Character> t_s = new Hashtable<Character, Character>();
int length = s.length();
for(int i = ; i < length; i++){
Character ss = s.charAt(i);
Character tt = t.charAt(i);
if(s_t.containsKey(ss) || t_s.containsKey(tt)){
if(s_t.get(ss) == tt && t_s.get(tt) == ss){
continue;
}else{
return false;
}
}else{
s_t.put(ss, tt);
t_s.put(tt, ss);
}
}
return true;
}
}