Is Sign of the Product of an Array easy or hard?

Sign of the Product of an Array is classified as an easy problem. The challenge is recognizing that you do not need to compute the actual product. Instead, tracking zeros and the parity of negative numbers leads to a straightforward O(n) solution.

Sign of the Product of an Array Python/Java solution

In Python or Java, iterate through the array and maintain a counter for negative numbers or a running sign variable. Return 0 if a zero is encountered. After the loop, determine whether the final sign is positive or negative based on the negative count parity. The logic remains identical across languages.

How to solve Sign of the Product of an Array in O(n)?

Iterate through the array and track two conditions: whether a zero exists and how many negative values appear. Return 0 immediately if a zero is found. If no zero exists, return 1 when the number of negatives is even and -1 when it is odd. This avoids computing the full product and prevents overflow.

What is the best approach for Sign of the Product of an Array?

The best approach scans the array once and counts negative numbers while checking for zero. If any element is zero, the result is 0. Otherwise, the product is positive when the negative count is even and negative when it is odd. This method runs in O(n) time and uses O(1) extra space.

Is Sign of the Product of an Array asked at Google/Amazon/Meta?

Variants of sign evaluation and product reasoning appear in interviews at companies like Amazon, Google, and Meta. While this exact problem is categorized as easy, it tests fundamental array traversal and mathematical reasoning, which frequently appear in screening rounds.

What data structure is used in Sign of the Product of an Array?

The solution primarily uses a simple array traversal. No additional data structures such as hash maps or stacks are required. Only constant variables are needed to track zero presence or the parity of negative numbers.

What is the time complexity of Sign of the Product of an Array?

The optimal solution runs in O(n) time because every element in the array must be inspected at least once. Space complexity is O(1) since only a few counters or a sign variable are maintained regardless of input size.

Description Hints 2 Solution Video 8:30

1822. Sign of the Product of an Array

Easy64.8% acceptance3 companies

Implement a function signFunc(x) that returns:

1 if x is positive.
-1 if x is negative.
0 if x is equal to 0.

You are given an integer array nums. Let product be the product of all values in the array nums.

Return signFunc(product).

Example 1:

Input: nums = [-1,-2,-3,-4,3,2,1]
Output: 1
Explanation: The product of all values in the array is 144, and signFunc(144) = 1

Example 2:

Input: nums = [1,5,0,2,-3]
Output: 0
Explanation: The product of all values in the array is 0, and signFunc(0) = 0

Example 3:

Input: nums = [-1,1,-1,1,-1]
Output: -1
Explanation: The product of all values in the array is -1, and signFunc(-1) = -1

Constraints:

1 <= nums.length <= 1000
-100 <= nums[i] <= 100

Asked at 3 companies

Microsoft Amazon Meta

Topics

Array Math

Hints open one at a time

Hint 1

If there is a 0 in the array the answer is 0

Hint 2

To avoid overflow make all the negative numbers -1 and all positive numbers 1 and calculate the prod

8:30

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

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

Starter codePython 3Spaces: 4

Examples

Case 1Case 2Case 3

Input

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

Input

[1,5,0,2,-3]

Input

[-1,1,-1,1,-1]

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