Python, LeetCode, 290. 单词模式

class Solution:
    def wordPattern(self, pattern, str):
        """
        :type pattern: str
        :type str: str
        :rtype: bool
        """
        if len(pattern) == 0 and len(str) == 0:  
            return True  
        pattern_dict = {}  
        str_list = str.split(' ')  
        str_set = set()
        if len(pattern) != len(str_list):
            return False
        for i in range(len(pattern)):  
            if pattern[i] in pattern_dict:  
                if str_list[i] != pattern_dict[pattern[i]]:  
                    return False  
                else:  
                    continue  
            else:  
                if str_list[i] in str_set:  
                    return False  
                else:  
                    pattern_dict[pattern[i]] = str_list[i]  
                    str_set.add(str_list[i])                  
        return True