Isomorphic Strings

题目描述：

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

"egg"

,

"add"

, return true.

Given

"foo"

,

"bar"

, return false.

Given

"paper"

,

"title"

, return true.

题目很简单，稍微注意一点:

这里s,t要相互比较才行，不然仅仅是isomorphic(s,t)的话，"ab","aa"也满足，事实是不符合题意的。

代码如下：

public class Solution {
public boolean isomorphic(String s, String t) {
Map<Character, Character> map=new HashMap<Character, Character>();
for(int i=0;i<s.length();i++){
if(!map.containsKey(s.charAt(i))){
map.put(s.charAt(i), t.charAt(i));
}else{
if(t.charAt(i)!=map.get(s.charAt(i)))
return false;
}
}
return true;
}

public boolean isIsomorphic(String s, String t) {
if(s.length()!=t.length())
return false;
return isomorphic(s, t)&& isomorphic(t, s);
}
}