Count Number of Nice Subarrays

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 are no odd numbers in the array.

Example 3:

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

class Solution {

    public int numberOfSubarrays(int[] nums, int k) {

        for(int i=0;i<nums.length;i++){

            if(nums[i]%2==0)

                nums[i] = 0;

            else

                nums[i] = 1;

        }

        return findAns(nums, k) - findAns(nums,k-1);

    }

    public int findAns(int [] nums, int k){

        int l = 0; 

        int r = 0; 

        int sum = 0;

        int count = 0;

        while(r<nums.length){

            sum = sum + nums[r];

            while(sum>k){

                sum = sum - nums[l];

                l++;

            }

            count = count + (r-l+1);

            r++;

        }

        return count;

    }

}