290. 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.

    public boolean wordPattern(String pattern, String str) {        String[] words = str.split(" ");        if(words.length!=pattern.length()) return false;        Map index = new HashMap();        for(Integer i=0; i<words.length;i++){            if(index.put(pattern.charAt(i), i)!=index.put(words[i], i)) return false;        }        return true;    }

总结：put 返回之前的值，如果map中存在某个key，且该key之前的值pattern match， 那么说明目前判断的也match