Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold

Problem Statement:

Given an array of integers arr and two integers k and threshold, return the number of sub-arrays of size k and average greater than or equal to threshold.

Example 1:

Input: arr = [2,2,2,2,5,5,5,8], k = 3, threshold = 4 Output: 3 Explanation: Sub-arrays [2,5,5],[5,5,5] and [5,5,8] have averages 4, 5 and 6 respectively. All other sub-arrays of size 3 have averages less than 4 (the threshold).

Example 2:

Input: arr = [11,13,17,23,29,31,7,5,2,3], k = 3, threshold = 5 Output: 6 Explanation: The first 6 sub-arrays of size 3 have averages greater than 5. Note that averages are not integers.

Constraints:

• 1 <= arr.length <= 10^5
• 1 <= arr[i] <= 10^4
• 1 <= k <= arr.length
• 0 <= threshold <= 10^4

Solution:

class Solution {
    public int numOfSubarrays(int[] arr, int k, int threshold) {
        int start = 0;
        int end = 0;
        int n = arr.length;
        Double sum = 0.0;
        int ans = 0;
 
        while(end < n){
            sum += arr[end];
            if(end - start + 1 == k){
                Double tempAvg = sum/k;
                if(tempAvg >= threshold){
                    ans++;
                }
                sum -= arr[start];
                start++;
            }
            end++;
        }
        return ans;
    }
}