# Concatenation of Array (LeetCode)

## 1929. Concatenation of Array (Easy)

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`

Hints:

Build an array of size 2 * n and assign num[i] to ans[i] and ans[i + n]

## Concatenation of Array (Java)

```class Solution {
public int[] getConcatenation(int[] nums) {
int[] ans = new int[2*nums.length];
for(int i=0; i<nums.length; i++)
{
ans[i]=nums[i];
ans[i+nums.length]=nums[i];
}
return ans;
}
}```