Is Array With Elements Not Equal to Average of Neighbors easy or hard?

The problem is rated Medium because the constraint is subtle. A naive rearrangement can accidentally produce an element equal to the average of its neighbors. Recognizing that sorting followed by controlled placement or zig-zag swaps prevents this condition requires a greedy insight.

Array With Elements Not Equal to Average of Neighbors Python/Java solution

Python and Java implementations typically follow the same logic: sort the array and rearrange it using either interleaving or zig-zag swaps. Python solutions often construct a new list for clarity, while Java implementations frequently perform in-place swaps to reduce memory usage. Both approaches run in O(n log n) time.

How to solve Array With Elements Not Equal to Average of Neighbors in O(n)?

Pure O(n) time is possible only if the input array is already sorted or nearly sorted. In that case, perform a single pass and swap adjacent elements at odd indices to create a zig-zag pattern. For arbitrary unsorted arrays, sorting is typically required, which raises the complexity to O(n log n).

What is the best approach for Array With Elements Not Equal to Average of Neighbors?

The most common approach is the sort and interleave strategy. Sort the array and place smaller values at even indices and larger values at odd indices so neighbors come from different value ranges. This prevents any element from becoming the exact average of its neighbors. The algorithm runs in O(n log n) time due to sorting and uses O(n) extra space.

Is Array With Elements Not Equal to Average of Neighbors asked at Google/Amazon/Meta?

Problems involving array rearrangement and greedy ordering frequently appear in interviews at companies like Amazon, Google, and Meta. While this exact problem may vary in wording, the underlying concept of preventing arithmetic relationships between neighbors is a common greedy interview pattern.

What data structure is used in Array With Elements Not Equal to Average of Neighbors?

The solution primarily uses arrays along with sorting algorithms. After sorting, a greedy rearrangement or swapping technique is applied to control the relationship between neighboring elements. No advanced data structures are required beyond the array itself.

What is the time complexity of Array With Elements Not Equal to Average of Neighbors?

Most optimal solutions run in O(n log n) time because the array is sorted first. After sorting, rearranging elements using interleaving or zig-zag swaps requires only a single linear pass. Space complexity ranges from O(1) for in-place swaps to O(n) when constructing a new reordered array.

Description Hints 2 Solution Video 7:04

1968. Array With Elements Not Equal to Average of Neighbors

Medium50.9% acceptance1 company

You are given a 0-indexed array nums of distinct integers. You want to rearrange the elements in the array such that every element in the rearranged array is not equal to the average of its neighbors.

More formally, the rearranged array should have the property such that for every i in the range 1 <= i < nums.length - 1, (nums[i-1] + nums[i+1]) / 2 is not equal to nums[i].

Return any rearrangement of nums that meets the requirements.

Example 1:

Input: nums = [1,2,3,4,5]
Output: [1,2,4,5,3]
Explanation:
When i=1, nums[i] = 2, and the average of its neighbors is (1+4) / 2 = 2.5.
When i=2, nums[i] = 4, and the average of its neighbors is (2+5) / 2 = 3.5.
When i=3, nums[i] = 5, and the average of its neighbors is (4+3) / 2 = 3.5.

Example 2:

Input: nums = [6,2,0,9,7]
Output: [9,7,6,2,0]
Explanation:
When i=1, nums[i] = 7, and the average of its neighbors is (9+6) / 2 = 7.5.
When i=2, nums[i] = 6, and the average of its neighbors is (7+2) / 2 = 4.5.
When i=3, nums[i] = 2, and the average of its neighbors is (6+0) / 2 = 3.

Constraints:

3 <= nums.length <= 10⁵
0 <= nums[i] <= 10⁵

Asked at 1 company

Uber

Topics

Hints open one at a time

Hint 1

A number can be the average of its neighbors if one neighbor is smaller than the number and the other is greater than the number.

Hint 2

We can put numbers smaller than the median on odd indices and the rest on even indices.

7:04

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