<p>Given a string <code>s</code> and an array of strings <code>words</code>, determine whether <code>s</code> is a <strong>prefix string</strong> of <code>words</code>.</p> <p>A string <code>s</code> is a <strong>prefix string</strong> of <code>words</code> if <code>s</code> can be made by concatenating the first <code>k</code> strings in <code>words</code> for some <strong>positive</strong> <code>k</code> no larger than <code>words.length</code>.</p> <p>Return <code>true</code><em> if </em><code>s</code><em> is a <strong>prefix string</strong> of </em><code>words</code><em>, or </em><code>false</code><em> otherwise</em>.</p> <p> </p> <p><strong class="example">Example 1:</strong></p> <pre> <strong>Input:</strong> s = "iloveleetcode", words = ["i","love","leetcode","apples"] <strong>Output:</strong> true <strong>Explanation:</strong> s can be made by concatenating "i", "love", and "leetcode" together. </pre> <p><strong class="example">Example 2:</strong></p> <pre> <strong>Input:</strong> s = "iloveleetcode", words = ["apples","i","love","leetcode"] <strong>Output:</strong> false <strong>Explanation:</strong> It is impossible to make s using a prefix of arr.</pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= words.length <= 100</code></li> <li><code>1 <= words[i].length <= 20</code></li> <li><code>1 <= s.length <= 1000</code></li> <li><code>words[i]</code> and <code>s</code> consist of only lowercase English letters.</li> </ul>