1929. Concatenation of Array

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`

1929. Concatenation of Array
``````struct Solution;

impl Solution {
fn get_concatenation(nums: Vec<i32>) -> Vec<i32> {
[nums.clone(), nums].concat()
}
}

#[test]
fn test() {
let nums = vec![1, 2, 1];
let res = vec![1, 2, 1, 1, 2, 1];
assert_eq!(Solution::get_concatenation(nums), res);
let nums = vec![1, 3, 2, 1];
let res = vec![1, 3, 2, 1, 1, 3, 2, 1];
assert_eq!(Solution::get_concatenation(nums), res);
}
``````