Skip to content

1248. Count Number of Nice Subarrays

Difficulty Topics

Description

Given an array of integers nums and an integer k. A continuous subarray is called nice if there are k odd numbers on it.

Return the number of nice sub-arrays.

 

Example 1:

Input: nums = [1,1,2,1,1], k = 3
Output: 2
Explanation: The only sub-arrays with 3 odd numbers are [1,1,2,1] and [1,2,1,1].

Example 2:

Input: nums = [2,4,6], k = 1
Output: 0
Explanation: There is no odd numbers in the array.

Example 3:

Input: nums = [2,2,2,1,2,2,1,2,2,2], k = 2
Output: 16

 

Constraints:

  • 1 <= nums.length <= 50000
  • 1 <= nums[i] <= 10^5
  • 1 <= k <= nums.length

Solution

count-number-of-nice-subarrays.py
class Solution:
    def numberOfSubarrays(self, nums: List[int], k: int) -> int:
        res = i = count = 0

        for j,x in enumerate(nums):
            if x & 1:
                k -= 1
                count = 0

            while k == 0:
                k += nums[i] & 1
                i += 1
                count += 1

            res += count

        return res