1816\. Truncate Sentence

Easy

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.