[leetcode]Isomorphic Strings

题目描述如下：

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.

题目真的不难，然而po主一开始用了数组去代替map然后在各种边界上出bug啊（感觉还是因为初始值的限制，加上昨天晚上实在是太困了所以脑子回路有点问题WA了很多遍），后来乖乖选择了用map进行记录，然后想偷懒不用两次映射结果最后反而TLE了。没办法，最后还是用了双向映射，代码如下：

public class Solution {
    public boolean isIsomorphic(String s, String t) {
        if (s.length() == 1) {
            return s.equals(t);
        }
        Map<Character, Character> isomorphicMap = new HashMap<Character, Character>();
        char s_mapKey, t_mapKey;
        for (int i = 0; i < s.length(); i++) {
            s_mapKey = s.charAt(i);
            t_mapKey = t.charAt(i);
            if (isomorphicMap.containsKey(s_mapKey)) {
                if (!(isomorphicMap.get(s_mapKey).equals(t_mapKey)))
                    return false;
            } else {
                isomorphicMap.put(s_mapKey, t_mapKey);
            }
        }
        isomorphicMap.clear();
        for (int i = 0; i < s.length(); i++) {
            s_mapKey = s.charAt(i);
            t_mapKey = t.charAt(i);
            if (isomorphicMap.containsKey(t_mapKey)) {
                if (!(isomorphicMap.get(t_mapKey).equals(s_mapKey)))
                    return false;
            } else {
                isomorphicMap.put(t_mapKey, s_mapKey);
            }
        }
        return true;
    }
}

题目链接：https://leetcode.com/problems/isomorphic-strings/