maximum-length-of-subarray-with-positive-product

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1567. Maximum Length of Subarray With Positive Product (Medium)

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

Related Topics

[Greedy]

Hints

Hint 1

Split the whole array into subarrays by zeroes since a subarray with positive product cannot contain any zero.

Hint 2

If the subarray has even number of negative numbers, the whole subarray has positive product.

Hint 3

Otherwise, we have two choices, either - remove the prefix till the first negative element in this subarray, or remove the suffix starting from the last negative element in this subarray.