The Shuffle the Array interview question gives you an array nums of 2n elements in the form [x1, x2, ..., xn, y1, y2, ..., yn]. Return the array shuffled to [x1, y1, x2, y2, ..., xn, yn]. This is a simple array interleaving problem — merge two halves by taking one element alternately from each half.
Uber, Microsoft, Meta, Amazon, Google, and Bloomberg ask this as a beginner-level exercise that tests array index arithmetic and the ability to interleave two sequences. It validates that candidates can translate the simple interleaving pattern into clean code without off-by-one errors. The problem also has an in-place variant (without extra space) that uses bit manipulation — a follow-up worth knowing.
The pattern is two-pointer interleaving. Use index i from 0 to n-1. For each i, append nums[i] (from the first half) followed by nums[i + n] (from the second half) to the result array. This produces the interleaved order in O(n) time and O(n) space. In Python: result = [val for i in range(n) for val in (nums[i], nums[i+n])].
nums = [2, 5, 1, 3, 4, 7], n = 3.
First half: [2, 5, 1]. Second half: [3, 4, 7].
Interleave:
Result: [2, 3, 5, 4, 1, 7].
nums[i + n] instead of nums[n + i] — same thing but worth double-checking the index arithmetic for the second half.n = len(nums) // 2 correctly — the two halves are each of length n.i from 0 to n-1 inclusive (range(n)), not range(2n).For the Shuffle the Array coding problem, the array interview pattern is the simplest two-half interleaving exercise. In Python, the list comprehension [val for i in range(n) for val in (nums[i], nums[i+n])] solves it in one line. Bloomberg and Microsoft interviewers may follow up: "Can you do this in O(1) extra space?" — the bit manipulation in-place approach packs both old and new values into each 32-bit integer temporarily (nums[i] |= nums[i+n] << 10 for values ≤ 1000). Know this optimization — it demonstrates bit manipulation depth beyond the basic solution.