day-181.cpp

/*
  Subarray Product Less Than K


Your are given an array of positive integers nums.

Count and print the number of (contiguous) subarrays where the product of all
the elements in the subarray is less than k.

Example 1:
Input: nums = [10, 5, 2, 6], k = 100
Output: 8
Explanation: The 8 subarrays that have product less than 100 are: [10], [5],
[2], [6], [10, 5], [5, 2], [2, 6], [5, 2, 6]. Note that [10, 5, 2] is not
included as the product of 100 is not strictly less than k. Note:

0 < nums.length <= 50000.
0 < nums[i] < 1000.
0 <= k < 10^6.

*/

// Solved using sliding window approach
class Solution {
   public:
    int numSubarrayProductLessThanK(vector<int>& nums, int k) {
        if (k == 0) return 0;
        int end = nums.size();
        int product = 1;
        int answer = 0;

        int left = 0;
        int right = 0;

        while (right < end) {
            product *= nums[right];

            while (left <= right && product >= k) {
                product /= nums[left];
                left += 1;
            }

            answer += right - left + 1;
            right += 1;
        }

        return answer;
    }
};