290 Word Pattern

Given apatternand a stringstr, find ifstrfollows the same pattern.
Here follow means a full match, such that there is a bijection between a letter inpatternand a non-empty word instr.
  1. 1.
    pattern = "abba", str = "dog cat cat dog" should return true.
  2. 2.
    pattern = "abba", str = "dog cat cat fish" should return false.
  3. 3.
    pattern = "aaaa", str = "dog cat cat dog" should return false.
  4. 4.
    pattern = "abba", str = "dog dog dog dog" should return false.
Notes: You may assumepatterncontains only lowercase letters, andstrcontains lowercase letters separated by a single space.
The Idea: Use a bidirectional map to check for a one to one mapping between each character in the pattern and each word in the sentence.
Complexity: O(n) time and O(2n) space:
def wordPattern(self, pattern, str):
:type pattern: str
:type str: str
:rtype: bool
if len(pattern) != len(str.split()):
return False
chars_word = {}
word_char = {}
for char, word in zip(pattern, str.split()):
if (chars_word.__contains__(char) and chars_word[char] != word)\
or word_char.__contains__(word) and word_char[word] != char:
return False
elif not chars_word.__contains__(char):
chars_word[char] = word
word_char[word] = char
return True