<p>The set <code>[1, 2, 3, ..., n]</code> contains a total of <code>n!</code> unique permutations.</p> <p>By listing and labeling all of the permutations in order, we get the following sequence for <code>n = 3</code>:</p> <ol> <li><code>"123"</code></li> <li><code>"132"</code></li> <li><code>"213"</code></li> <li><code>"231"</code></li> <li><code>"312"</code></li> <li><code>"321"</code></li> </ol> <p>Given <code>n</code> and <code>k</code>, return the <code>k<sup>th</sup></code> permutation sequence.</p> <p> </p> <p><strong>Example 1:</strong></p> <pre><strong>Input:</strong> n = 3, k = 3 <strong>Output:</strong> "213" </pre><p><strong>Example 2:</strong></p> <pre><strong>Input:</strong> n = 4, k = 9 <strong>Output:</strong> "2314" </pre><p><strong>Example 3:</strong></p> <pre><strong>Input:</strong> n = 3, k = 1 <strong>Output:</strong> "123" </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= n <= 9</code></li> <li><code>1 <= k <= n!</code></li> </ul>