Problem
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].
Constraints:
1 <= nums.length <= 10^5-10^9 <= nums[i] <= 10^9
Solution (Java)
class Solution {
public int getMaxLen(int[] nums) {
int posLen = 0;
int negLen = 0;
int res = 0;
for (int num : nums) {
if (num == 0) {
posLen = 0;
negLen = 0;
} else if (num > 0) {
posLen++;
negLen = negLen == 0 ? 0 : negLen + 1;
} else {
int temp = posLen;
posLen = negLen == 0 ? 0 : negLen + 1;
negLen = temp + 1;
}
res = Math.max(res, posLen);
}
return res;
}
}
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).