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

# 1816. Truncate Sentence

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);
for (int i = 1; i < k; i++)
sb.append(" " + array[i]);
return sb.toString();
}
}