LeetCode 1816. Truncate Sentence

Description

https://leetcode.com/problems/truncate-sentence/

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"

Constraints:

  • 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.

Explanation

Splits the word and keeps only the first k words to build a new string sentence.

Python Solution

class Solution:
    def truncateSentence(self, s: str, k: int) -> str:
        words = s.split()
        
        return " ".join(words[:k])
  • Time Complexity: O(N).
  • Space Complexity: O(N).

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