Is Shuffle the Array easy or hard?

Shuffle the Array is classified as an Easy problem on LeetCode with a very high acceptance rate. The task mainly checks whether you can recognize a simple indexing pattern and implement an O(n) array traversal.

Shuffle the Array Python/Java solution

In Python or Java, the typical implementation uses two pointers and a result array. Iterate i from 0 to n-1 and append nums[i] followed by nums[i+n]. The logic is identical across languages and runs in O(n) time.

How to solve Shuffle the Array in O(n)?

Iterate through the first half of the array while pairing elements with the second half. For every index i from 0 to n-1, append nums[i] and nums[i+n] to the result. This processes all elements exactly once, giving O(n) time complexity.

What is the best approach for Shuffle the Array?

The two-pointer technique is the best and most readable approach. Start one pointer at index 0 and another at index n, then append elements alternately to a new array. This runs in O(n) time with O(n) extra space and directly matches the required output structure.

Is Shuffle the Array asked at Google/Amazon/Meta?

Shuffle the Array is a common beginner-level array problem seen in coding practice and early interview rounds. Variations of array interleaving or index mapping appear in interviews at companies like Amazon and Meta when testing basic array manipulation skills.

What data structure is used in Shuffle the Array?

The problem primarily uses arrays. Most solutions rely on sequential traversal of the array, sometimes combined with the two-pointer pattern or bit/number encoding techniques for in-place transformations.

What is the time complexity of Shuffle the Array?

Both common solutions run in O(n) time because each element is processed once. The standard two-pointer solution uses O(n) extra space for the result array, while the in-place encoding method reduces auxiliary space to O(1).

Description Hints 1 Solution Video 10:15

1470. Shuffle the Array

Easy88.7% acceptance6 companies

Given the array nums consisting of 2n elements in the form [x₁,x₂,...,x_n,y₁,y₂,...,y_n].

Return the array in the form [x₁,y₁,x₂,y₂,...,x_n,y_n].

Example 1:

Input: nums = [2,5,1,3,4,7], n = 3
Output: [2,3,5,4,1,7] 
Explanation: Since x₁=2, x₂=5, x₃=1, y₁=3, y₂=4, y₃=7 then the answer is [2,3,5,4,1,7].

Example 2:

Input: nums = [1,2,3,4,4,3,2,1], n = 4
Output: [1,4,2,3,3,2,4,1]

Example 3:

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

Constraints:

1 <= n <= 500
nums.length == 2n
1 <= nums[i] <= 10^3

Asked at 6 companies

Morgan Stanley

Google Amazon Microsoft Bloomberg Meta

Topics

Array

Hints open one at a time

Hint 1

Use two pointers to create the new array of 2n elements. The first starting at the beginning and the other starting at (n+1)th position. Alternate between them and create the new array.

10:15

Still stuck?Read 3 approaches, or watch a walkthrough.

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1class Solution:
2    def shuffle(self, nums: List[int], n: int) -> List[int]:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2Case 3

Input

[2,5,1,3,4,7]
3

Input

[1,2,3,4,4,3,2,1]
4

Input

[1,1,2,2]
2

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