# Count subarrays with element product less than target

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Your are given an array of positive integers numbers.

Count and print the number of (contiguous) sub-arrays where the product of all the elements in the sub-array 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.
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Simple Java code:-

class Solution {
public int numSubarrayProductLessThanK(int[] nums, int k) {
int product = 1, left = 0, count = 0;
for (int right = 0; right < nums.length; right++) {
product *= nums[right];
while (product >= k && left < nums.length)
product /= nums[left++];
if (right > left - 1)
count += (right - left) + 1;
}
return count;
}
}

Javascript option

/**
* @param {number[]} nums
* @param {number} k
* @return {number}
*/
var numSubarrayProductLessThanK = function(nums, k) {
var product = 1, left = 0, count = 0;
for (var right = 0; right < nums.length; right++) {
product *= nums[right];
while (product >= k && left < nums.length)
product /= nums[left++];
if (right > left - 1)
count += (right - left) + 1;
}
return count;
};

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