Leetcode Word Pattern

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

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:

1. Both pattern and str contains only lowercase alphabetical letters.
2. Both pattern and str do not have leading or trailing spaces.
3. Each word in str is separated by a single space.
4. Each letter in pattern must map to a word with length that is at least 1.

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 解题思路：

使用HashMap, pattern 里的character 对应str 里的word.

注意：pattern = "abba", str = "dog dog dog dog" should return false.

即当map里不包含key 时，还要检查是否已包含Value, 如果已含，那么return false.

另外，分割space 使用str.split("\s+")

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Java code:

public boolean wordPattern(String pattern, String str) {
         String[] splited = str.split("\s+");
         if(pattern.length() != splited.length) {
             return false;
         }
         Map<Character, String> map = new HashMap<Character, String>();
         for(int i = 0; i < pattern.length(); i++){
             if(!map.containsKey(pattern.charAt(i))) {
                 if(map.containsValue(splited[i])){
                     return false;
                 }
                 map.put(pattern.charAt(i), splited[i]);
             }else{
                 if(!map.get(pattern.charAt(i)).equals(splited[i])){
                     return false;
                 }
             }
         }
         return true;
    }