Concatenation of Array (LeetCode)

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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;
    }
}

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