# 0713. Subarray Product Less Than K

<https://leetcode.com/problems/subarray-product-less-than-k>

## Description

Given an array of integers `nums` and an integer `k`, return *the number of contiguous subarrays where the product of all the elements in the subarray is strictly 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.
```

**Example 2:**

```
**Input:** nums = [1,2,3], k = 0
**Output:** 0
```

**Constraints:**

* `1 <= nums.length <= 3 * 104`
* `1 <= nums[i] <= 1000`
* `0 <= k <= 106`

## ac

```java
class Solution {
    public int numSubarrayProductLessThanK(int[] nums, int k) {
        // edge cases
        if (nums == null || nums.length == 0 || k <= 1) return 0;

        int windowProduct = 1;
        int count = 0;

        for (int r = 0, l = 0; r < nums.length; r++) {
            windowProduct *= nums[r];

            while (windowProduct >= k) {
                windowProduct /= nums[l];
                l++;
            }

            count += r - l + 1;  // when a new element add to right, it forms window size new subarray
        }

        return count;
    }
}

/*
key: how to process the window
sliding window idea: when window formed, do something.
*/
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://jaywin.gitbook.io/leetcode/solutions/0713-subarray-product-less-than-k.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.