<p>Given an integer array <code>nums</code> of length <code>n</code>, you want to create an array <code>ans</code> of length <code>2n</code> where <code>ans[i] == nums[i]</code> and <code>ans[i + n] == nums[i]</code> for <code>0 <= i < n</code> (<strong>0-indexed</strong>).</p> <p>Specifically, <code>ans</code> is the <strong>concatenation</strong> of two <code>nums</code> arrays.</p> <p>Return <em>the array </em><code>ans</code>.</p> <p> </p> <p><strong>Example 1:</strong></p> <pre> <strong>Input:</strong> nums = [1,2,1] <strong>Output:</strong> [1,2,1,1,2,1] <strong>Explanation:</strong> The array ans is formed as follows: - ans = [nums[0],nums[1],nums[2],nums[0],nums[1],nums[2]] - ans = [1,2,1,1,2,1]</pre> <p><strong>Example 2:</strong></p> <pre> <strong>Input:</strong> nums = [1,3,2,1] <strong>Output:</strong> [1,3,2,1,1,3,2,1] <strong>Explanation:</strong> The array ans is formed as follows: - ans = [nums[0],nums[1],nums[2],nums[3],nums[0],nums[1],nums[2],nums[3]] - ans = [1,3,2,1,1,3,2,1] </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>n == nums.length</code></li> <li><code>1 <= n <= 1000</code></li> <li><code>1 <= nums[i] <= 1000</code></li> </ul>