1822

1822. Sign of the Product of an Array (Easy)

There is 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

Related Topics:
Math

Solution 1. Count negative numbers

• If there is any 0, return 0.
• Otherwise, return -1 if there are odd number of negative numbers; otherwise 1.

// OJ: https://leetcode.com/problems/sign-of-the-product-of-an-array/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    int arraySign(vector<int>& A) {
        int cnt = 0;
        for (int n : A) {
            if (n == 0) return 0;
            cnt += n < 0;
        }
        return cnt % 2 ? -1 : 1;
    }
};