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.
解题思路：
用两张图保存下两个方向的映射即可，JAVA实现如下：
public boolean isIsomorphic(String s, String t) {
HashMap<Character, Character> hm = new HashMap<Character, Character>();
HashMap<Character, Character> hm2 = new HashMap<Character, Character>();
for (int i = 0; i < s.length(); i++) {
if (hm.containsKey(s.charAt(i))
&& hm.get(s.charAt(i)) != t.charAt(i))
return false;
hm.put(s.charAt(i), t.charAt(i));
if (hm2.containsKey(t.charAt(i))
&& hm2.get(t.charAt(i)) != s.charAt(i))
return false;
hm2.put(t.charAt(i), s.charAt(i));
}
return true;
}
Java for LeetCode 205 Isomorphic Strings
原文：http://www.cnblogs.com/tonyluis/p/4558936.html