Longest Even Odd Subarray With Threshold — LeetCode 2760 Python Solution

The problem

You are given a 0-indexed integer array nums and an integer threshold. Find the length of the longest subarray of nums starting at index l and ending at index r (0 <= l <= r < nums.length) that satisfies the following conditions: nums[l] % 2 == 0 For all indices i in the range [l, r - 1], nums[i] % 2 != nums[i + 1] % 2 For all indices i in the range [l, r], nums[i] <= threshold Return an integer denoting the length of the longest such subarray.

Example

Input

nums = [3,2,5,4], threshold = 5

Output

3

Explanation

In this example, we can select the subarray that starts at l = 1 and ends at r = 3 => [2,5,4]. This subarray satisfies the conditions.

Python solution

class Solution:
    def longestAlternatingSubarray(self, nums: List[int], threshold: int) -> int:
        ans, n = 0, len(nums)
        for l in range(n):
            if nums[l] % 2 == 0 and nums[l] <= threshold:
                r = l + 1
                while r < n and nums[r] % 2 != nums[r - 1] % 2 and nums[r] <= threshold:
                    r += 1
                ans = max(ans, r - l)
        return ans

Complexity

Pattern: Sliding Window

Collapse a nested loop over every subarray into a single pass with two indices. LeetCode 2760. Longest Even Odd Subarray With Threshold is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Sliding Window.

The sliding window guide has the Python template for the pattern and the 116 LeetCode problems that use it.

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