Given an integer array?nums?of length?n, you want to create an array?ans?of length?2n?where?ans[i] == nums[i]?and?ans[i + n] == nums[i]?for?0 <= i < n?(0-indexed).

Specifically,?ans?is the?concatenation?of two?nums?arrays.

Return?the array?ans.

?

Example 1:

Input: nums = [1,2,1]Output: [1,2,1,1,2,1]Explanation: 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]

Example 2:

Input: nums = [1,3,2,1]Output: [1,3,2,1,1,3,2,1]Explanation: 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]

?

Constraints:

• n == nums.length

• 1 <= n <= 1000

• 1 <= nums[i] <= 1000

Runtime:?0 ms, faster than?100.00%?of?Java?online submissions for?Concatenation of Array.

Memory Usage:?42.6 MB, less than?95.59%?of?Java?online submissions for?Concatenation of Array.

屬于很簡(jiǎn)單的一道題了，沒(méi)啥說(shuō)的了。