33.Word Pattern

Given a pattern and a string str, find if str follows the same pattern.

Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty word in str.

Examples:

1. pattern = "abba", str = "dog cat cat dog" should return true.
2. pattern = "abba", str = "dog cat cat fish" should return false.
3. pattern = "aaaa", str = "dog cat cat dog" should return false.
4. pattern = "abba", str = "dog dog dog dog" should return false.

Notes:
You may assume pattern contains only lowercase letters, and str contains lowercase letters separated by a single space.

分析：

1.用map存储字符与字符串间的对应关系

2.如果map中已经存了这个字符，则判断当前value与map中存的oldvalue是否相同，不相同则返回false，相同则继续。

3.如果map中尚未存了这个字符，但是已经有了这个value，则返回false。否则加入<key,value>