LeetCode-in-Java

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

Solution

public class Solution {
    public int[] getConcatenation(int[] nums) {
        int[] result = new int[nums.length * 2];
        System.arraycopy(nums, 0, result, 0, nums.length);
        int i = nums.length;
        for (int j = 0; i < result.length && j < nums.length; i++, j++) {
            result[i] = nums[j];
        }
        return result;
    }
}

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