algoadvance

1. 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]

Example 2:

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

Clarifying Questions

1. Q: Are the elements in nums guaranteed to be integers? A: Yes, the problem statement specifies an integer array.

2. Q: Can nums be empty? A: According to the problem description, no constraints are specified regarding the emptiness of the nums array. It’s assumed to be a non-empty array as per usual array input conventions in such problems.

3. Q: Is there a constraint on the size of nums? A: The typical constraint for such problems is usually around 1 <= nums.length <= 1000 and -1000 <= nums[i] <= 1000, but these specifics would normally be found in the problem details.

Strategy

The problem can be solved directly using list concatenation operations in Python:

1. Take the input nums array.
2. Concatenate it with itself to form the required result.

The naive and efficient way to achieve this is by using the + operator to concatenate the list with itself.

Code

def getConcatenation(nums: List[int]) -> List[int]:
    return nums + nums

Time Complexity

• Time Complexity: O(n), where n is the length of the input array nums. This is because the list concatenation involves copying each element exactly once.
• Space Complexity: O(n), because we are creating a new list of size 2n.

This approach should efficiently solve the given problem within the typical constraints expected in such coding interviews.

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