描述
A sentence is a list of words that are separated by a single space with no leading or trailing spaces. Each of the words consists of only uppercase and lowercase English letters (no punctuation).
- For example, "Hello World", "HELLO", and "hello world hello world" are all sentences.
You are given a sentence s and an integer k. You want to truncate s such that it contains only the first k words. Return s after truncating it.
Example 1:
Input: s = "Hello how are you Contestant", k = 4
Output: "Hello how are you"
Explanation:
The words in s are ["Hello", "how" "are", "you", "Contestant"].
The first 4 words are ["Hello", "how", "are", "you"].
Hence, you should return "Hello how are you".
Example 2:
Input: s = "What is the solution to this problem", k = 4
Output: "What is the solution"
Explanation:
The words in s are ["What", "is" "the", "solution", "to", "this", "problem"].
The first 4 words are ["What", "is", "the", "solution"].
Hence, you should return "What is the solution".
Example 3:
Input: s = "chopper is not a tanuki", k = 5
Output: "chopper is not a tanuki"
Note:
1 <= s.length <= 500
k is in the range [1, the number of words in s].
s consist of only lowercase and uppercase English letters and spaces.
The words in s are separated by a single space.
There are no leading or trailing spaces.
解析
根据题意，就是将句子中的前 k 个单词用空格拼接起来，用内置函数也就两行代码，我这里自己直接遍历字符串，通过判断拼接得到最后的结果，这或许就是自己给自己增加难度吧。
解答
class Solution(object):
def truncateSentence(self, s, k):
"""
:type s: str
:type k: int
:rtype: str
"""
r = ''
index = 0
while k and index<len(s):
if s[index]==' ':
if index==0:
index += 1
elif index>=1 and s[index-1]==' ':
index += 1
elif index>=1 and s[index-1]!=' ':
index += 1
k -= 1
if k>=1:
r += ' '
elif s[index]!=' ':
r += s[index]
index += 1
return r
运行结果
Runtime: 16 ms, faster than 80.21% of Python online submissions for Truncate Sentence.
Memory Usage: 13.6 MB, less than 41.33% of Python online submissions for Truncate Sentence.
解析
使用内置函数
解答
class Solution(object):
def truncateSentence(self, s, k):
"""
:type s: str
:type k: int
:rtype: str
"""
words = s.split(" ")
return " ".join(words[0:k])
运行结果
Runtime: 12 ms, faster than 96.92% of Python online submissions for Truncate Sentence.
Memory Usage: 13.3 MB, less than 93.33% of Python online submissions for Truncate Sentence.
原题链接：leetcode.com/problems/tr…
您的支持是我最大的动力
