1822. Sign of An Array - Explanation

1. Count Negative Numbers

class Solution:
    def arraySign(self, nums: list[int]) -> int:
        neg = 0
        for num in nums:
            if num == 0:
                return 0
            neg += (1 if num < 0 else 0)
        return -1 if neg % 2 else 1

Time & Space Complexity

Time complexity: $O(n)$
Space complexity: $O(1)$

2. Track the Sign of the Product

class Solution:
    def arraySign(self, nums: list[int]) -> int:
        sign = 1
        for num in nums:
            if num == 0:
                return 0
            if num < 0:
                sign *= -1
        return sign

Time & Space Complexity

Time complexity: $O(n)$
Space complexity: $O(1)$