1929. Concatenation of Array

https://leetcode.com/problems/concatenation-of-array

Description

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

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