ConcatenationOfArray.java

//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

import java.io.*;
import java.lang.*;
import java.util.*;

public class ConcatenationOfArray {
    public int[] getConcatenation(int[] nums) {

        int[] ans = new int[nums.length * 2];

        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) {
        ConcatenationOfArray concat = new ConcatenationOfArray();
        int[] nums = new int[]{1, 2, 3, 1};
        System.out.println(Arrays.toString(concat.getConcatenation(nums)));;
    }
}