Formatted question description: https://leetcode.ca/all/1816.html

1816. Truncate Sentence

Level

Easy

Description

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”

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.

Solution

Split s into an array using spaces. Then generate the truncated sentence by concatenating the first k elements of the array, and return the truncated sentence.

class Solution {
    public String truncateSentence(String s, int k) {
        String[] array = s.split(" ");
        StringBuffer sb = new StringBuffer(array[0]);
        for (int i = 1; i < k; i++)
            sb.append(" " + array[i]);
        return sb.toString();
    }
}

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