443. String Compression

1343. Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold

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.

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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).

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Example 2:

Input: arr = [1,1,1,1,1], k = 1, threshold = 0
Output: 5

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Example 3:

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.

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Example 4:

Input: arr = [7,7,7,7,7,7,7], k = 7, threshold = 7
Output: 1


Example 5:

Input: arr = [4,4,4,4], k = 4, threshold = 1
Output: 1

Constraints:

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

Solution

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class Solution {
    public int numOfSubarrays(int[] arr, int k, int threshold) {
        int n = arr.length;
        int count = 0;
        double avg = 0;
        for (int i = 0; i < k && i < n; i++) {
            avg = avg + arr[i];
        }
        avg = avg / (double) k;
        if (avg >= threshold) count++;
        int i = k;
        while (i < n) {
            avg = avg - arr[i - k] / k + arr[i] / k;
            if (avg >= threshold) count++;
            i++;
            
        }
        return count;
    }
}

Solution#

Solution