作者: 负雪明烛
id: fuxuemingzhu
个人博客: http://fuxuemingzhu.cn/
题目地址:https://leetcode.com/problems/uncommon-words-from-two-sentences/description/
We are given two sentences A
and B
. (A sentence is a string of space separated words. Each word consists only of lowercase letters.)
A word is uncommon if it appears exactly once in one of the sentences, and does not appear in the other sentence.
Return a list of all uncommon words.
You may return the list in any order.
Example 1:
Input: A = "this apple is sweet", B = "this apple is sour"
Output: ["sweet","sour"]
Example 2:
Input: A = "apple apple", B = "banana"
Output: ["banana"]
Note:
如果一个词在一句话中只出现了一次,在另外一句话中没出现,那么这个词是不同的词。找出两句话中所有不同的词。
统计一下两句话单词的set,找出两个set的不同词,然后再判断这个词是否只出现了1次,如果只出现了1次,即为题目所求。
注意,要先找不同词,然后再判断是否出现1次。如这个测试用例:
Input:
"s z z z s"
"s z ejt"
Output:
["ejt","s","z"]
Expected:
["ejt"]
不可以先去重组成set,然后再求。。也就是说,只要一个词在一句话中出现的次数超过了1次,那么一定会被排除掉。
另外注意,这其实是求下面这个图的A+B部分。在python3中的Counter.keys是个set,可以直接做交并补操作。
代码如下:
class Solution:
def uncommonFromSentences(self, A, B):
"""
:type A: str
:type B: str
:rtype: List[str]
"""
count_A = collections.Counter(A.split(' '))
count_B = collections.Counter(B.split(' '))
words = list((count_A.keys() | count_B.keys()) - (count_A.keys() & count_B.keys()))
ans = []
for word in words:
if count_A[word] == 1 or count_B[word] == 1:
ans.append(word)
return ans
2018 年 8 月 16 日 —— 一个月不写题,竟然啥都不会了。。加油!
2018 年 11 月 8 日 —— 项目进展缓慢
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