Java Program for Concatenation of Array.

Given an integer array nums of length n, create a new array ans of length 2n such that ans is the concatenation of two nums arrays. 

Example:
Input: nums = [1, 2, 4]
Output: ans = [1, 2, 4, 1, 2, 4]

Input: nums = [1, 3, 2, 1]
Output: ans = [1, 3, 2, 1, 1, 3, 2, 1]

Steps:

• Create a new array ans[] = new int[2*n] of size 2n where n is the size of the given array. 
• Copy the elements given into the new array where ans[i] = nums[i] and ans[i+n] = nums[i]. 
• Return ans.

public class Main

{

    public static 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;

    }

public static void main(String[] args) {

    int nums[] = {1, 2, 1, 3};

    

    int[] ans = getConcatenation(nums);

    

    for(int i = 0; i<ans.length; i++) {

        System.out.print(ans[i]+" ");

    }

}

}