leetcode 1567 - Maximum Length of Subarray With Positive Product

https://leetcode.com/problems/maximum-length-of-subarray-with-positive-product/

Given an array of integers nums, find the maximum length of a subarray where the product of all its elements is positive.

A subarray of an array is a consecutive sequence of zero or more values taken out of that array.

Return the maximum length of a subarray with positive product.

Example 1:

Input: nums = [1,-2,-3,4]
Output: 4
Explanation: The array nums already has a positive product of 24.
Example 2:

Input: nums = [0,1,-2,-3,-4]
Output: 3
Explanation: The longest subarray with positive product is [1,-2,-3] which has a product of 6.
Notice that we cannot include 0 in the subarray since that’ll make the product 0 which is not positive.
Example 3:

Input: nums = [-1,-2,-3,0,1]
Output: 2
Explanation: The longest subarray with positive product is [-1,-2] or [-2,-3].
Example 4:

Input: nums = [-1,2]
Output: 1
Example 5:

Input: nums = [1,2,3,5,-6,4,0,10]
Output: 4

Constraints:

1 <= nums.length <= 10^5
-10^9 <= nums[i] <= 10^9

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
class Solution {
public:
int getMaxLen(vector<int>& nums) {
int positive = 0, negative = 0;

int max_len = 0;

for (int num : nums) {
if (num > 0) {
positive++;
if (negative)
negative++;
} else if (num < 0) {
int old_positive = positive;
int old_negative = negative;

if (old_positive > 0)
negative = old_positive + 1;
else
negative = 1;

if (old_negative > 0)
positive = old_negative + 1;
else
positive = 0;
} else {
positive = negative = 0;
}

max_len = max(max_len, positive);
}


return max_len;
}
};