LeetCode----Word Pattern

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:

pattern = 

"abba"

, str = 

"dog
cat cat dog"

 should return true.
pattern = 

"abba"

, str = 

"dog
cat cat fish"

 should return false.
pattern = 

"aaaa"

, str = 

"dog
cat cat dog"

 should return false.
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：

按模式匹配给定字符串。

我的做法是，先讲模式如“aabb”，构造成模式字典pd＝{'a':None, 'b':None}。再将给定串如“dog dog cat cat”按空格切分。然后，按顺序去对应串和字典中键，如果不匹配则不符合该模式。最后，再判断字典中不同键值对应的串是否相同，如果相同，也不符合该模式。

代码：

class Solution(object):
def wordPattern(self, pattern, str):
"""
:type pattern: str
:type str: str
:rtype: bool
"""
pd = dict(map(lambda a: (a, None), list(pattern)))
slst = str.split()
if len(pattern) != len(slst):
return False
for i in range(len(slst)):
if pd[pattern[i]] is None:
pd[pattern[i]] = slst[i]
else:
if pd[pattern[i]] != slst[i]:
return False
s = set()
for i in pd:
s.add(pd[i])
if len(s) != len(pd):
return False
return True