Truncate Sentence
<p>A <strong>sentence</strong> is a list of words that are separated by a single space with no leading or trailing spaces. Each of the words consists of <strong>only</strong> uppercase and lowercase English letters (no punctuation).</p>

<ul>
	<li>For example, <code>&quot;Hello World&quot;</code>, <code>&quot;HELLO&quot;</code>, and <code>&quot;hello world hello world&quot;</code> are all sentences.</li>
</ul>

<p>You are given a sentence <code>s</code>​​​​​​ and an integer <code>k</code>​​​​​​. You want to <strong>truncate</strong> <code>s</code>​​​​​​ such that it contains only the <strong>first</strong> <code>k</code>​​​​​​ words. Return <code>s</code>​​​​<em>​​ after <strong>truncating</strong> it.</em></p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;Hello how are you Contestant&quot;, k = 4
<strong>Output:</strong> &quot;Hello how are you&quot;
<strong>Explanation:</strong>
The words in s are [&quot;Hello&quot;, &quot;how&quot; &quot;are&quot;, &quot;you&quot;, &quot;Contestant&quot;].
The first 4 words are [&quot;Hello&quot;, &quot;how&quot;, &quot;are&quot;, &quot;you&quot;].
Hence, you should return &quot;Hello how are you&quot;.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;What is the solution to this problem&quot;, k = 4
<strong>Output:</strong> &quot;What is the solution&quot;
<strong>Explanation:</strong>
The words in s are [&quot;What&quot;, &quot;is&quot; &quot;the&quot;, &quot;solution&quot;, &quot;to&quot;, &quot;this&quot;, &quot;problem&quot;].
The first 4 words are [&quot;What&quot;, &quot;is&quot;, &quot;the&quot;, &quot;solution&quot;].
Hence, you should return &quot;What is the solution&quot;.</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;chopper is not a tanuki&quot;, k = 5
<strong>Output:</strong> &quot;chopper is not a tanuki&quot;
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 500</code></li>
	<li><code>k</code> is in the range <code>[1, the number of words in s]</code>.</li>
	<li><code>s</code> consist of only lowercase and uppercase English letters and spaces.</li>
	<li>The words in <code>s</code> are separated by a single space.</li>
	<li>There are no leading or trailing spaces.</li>
</ul>
Array; String
class Solution {
public:
    string truncateSentence(string s, int k) {
        for (int i = 0; i < s.size(); ++i) {
            if (s[i] == ' ' && (--k) == 0) {
                return s.substr(0, i);
            }
        }
        return s;
    }
};