_1343.java

package com.fishercoder.solutions;

/**
 * 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.
 *
 * 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 = [1,1,1,1,1], k = 1, threshold = 0
 * Output: 5
 *
 * 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.
 *
 * 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
 * */
public class _1343 {
    public static class Solution1 {
        public int numOfSubarrays(int[] arr, int k, int threshold) {
            int sum = 0;
            for (int i = 0; i < k - 1; i++) {
                sum += arr[i];
            }
            int count = 0;
            for (int i = k - 1; i < arr.length; i++) {
                sum += arr[i];
                if (i - k >= 0) {
                    sum -= arr[i - k];
                }
                if (sum / k >= threshold) {
                    count++;
                }
            }
            return count;
        }
    }
}