ans1.js

//Concatenation of Array

/*
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]
*/

//Solution

var getConcatenation = function(nums) {
    //   const ans=[...nums,...nums]
    //    return ans
        let n=nums.length;
        let ans=new Array(2n)
        for(let i=0;i<n;i++){
            ans[i]=nums[i];
            ans[i+n]=nums[i]
        }
        return ans
    };

    console.log(getConcatenation([1,2,1]))