Leetcode problem 25 - Recyclable and Low Fat Products

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]

/**
 * @param {number[]} nums
 * @return {number[]}
 */
var getConcatenation = function (nums) {
  let leng = nums.length;
  for (let i = 0; i < leng; i++) {
    nums.push(nums[i]);
  }

  return nums;
};

The function getConcatenation takes an array nums as its parameter.

It initializes a variable leng and assigns it the value of the length of the nums array.

The function uses a for loop to iterate through each element of the nums array.

Inside the loop, it pushes the current element (nums[i]) into the nums array using the nums.push() method. This effectively appends the element to the end of the array.

The loop iterates leng times, and each time it pushes the current element to the end of the array. As a result, the nums array is effectively concatenated with itself.

After the loop, the function returns the resulting nums array, which contains the concatenation of the original array with itself.