describe

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".
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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".
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Example 3:

Input: s = "chopper is not a tanuki", k = 5
Output: "chopper is not a tanuki"
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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.
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parsing

The first k words in the sentence are concatenated with Spaces. There are only two lines of code using the built-in function. Here, I directly traverse the string and get the final result by judging the concatenation, which may be to increase the difficulty for myself.

answer

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 rCopy the code

The results

Given in the Python online submissions. Memory Usage: 10 ms Given in the Python online submissions for Truncate Sentence.Copy the code

parsing

Using built-in functions

answer

class Solution(object):
    def truncateSentence(self, s, k):
        """
        :type s: str
        :type k: int
        :rtype: str
        """
        words = s.split(" ")
        return " ".join(words[0:k])
        	      
		
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The results

Given in the Python online submissions. Memory Usage: 10 ms Given in the Python online submissions for Truncate Sentence.Copy the code

Original link: leetcode.com/problems/tr…

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