Problem Statement:

You are given an integer array nums of length n. The task is to create a new array ans of length 2n such that ans[i] == nums[i] and ans[i + n] == nums[i] for 0 <= i < n (0-indexed). In simpler terms, the array ans is formed by concatenating two copies of the array nums.

Solution Approach:

To solve this problem, we can iterate over the indices of the new array ans, which has a length of 2n. At each index i, we assign the value of nums[i % n] to ans[i]. This effectively cycles through the elements of nums twice to fill up the ans array.

Let's break down the steps of the solution:

  1. Calculate the length of the input array:First, we determine the length of the input array nums and store it in a variable n.
  2. Initialize an empty array to store the result:We create an empty array ans where we will store the concatenated array.
  3. Iterate over indices of the new array:Using a for loop, we iterate over the indices of the new array ans, which ranges from 0 to 2n - 1.
  4. Assign values to the new array:At each index i, we assign the value of nums[i % n] to ans[i]. Here, i % n ensures that we cycle through the elements of nums.
  5. Return the concatenated array:Finally, we return the concatenated array ans as the result.

Python Code with Comments:

from typing import List

class Solution:
    def getConcatenation(self, nums: List[int]) -> List[int]:
        # Calculate the length of the input array
        n = len(nums)
        
        # Initialize an empty array to store the concatenated array
        ans = []
        
        # Iterate over indices of the new array
        for i in range(2 * n):
            # Assign values to the new array
            ans.append(nums[i % n])  # Cycling through the elements of nums
            
        # Return the concatenated array
        return ans

# Example usage:
# nums = [1, 2, 3]
# solution = Solution()
# concatenated_array = solution.getConcatenation(nums)
# print(concatenated_array)

Conclusion:

In this post, we've discussed a coding problem that involves concatenating an integer array with itself to create a new array. We've provided a step-by-step explanation of the solution approach and presented the corresponding Python code with comments to help you understand the implementation. I hope this blog post has been helpful in understanding how to solve this problem efficiently in Python. Thank you for reading!