713. 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`.
• 713. Subarray Product Less Than K
``````struct Solution;

impl Solution {
fn num_subarray_product_less_than_k(nums: Vec<i32>, k: i32) -> i32 {
let n = nums.len();
let mut i = 0;
let mut product = 1;
let mut res = 0;
for j in 0..n {
product *= nums[j];
while i <= j && product >= k {
product /= nums[i];
i += 1;
}
res += (j + 1 - i) as i32;
}
res
}
}

#[test]
fn test() {
let nums = vec![10, 5, 2, 6];
let k = 100;
let res = 8;
assert_eq!(Solution::num_subarray_product_less_than_k(nums, k), res);
let nums = vec![1, 2, 3];
let k = 0;
let res = 0;
assert_eq!(Solution::num_subarray_product_less_than_k(nums, k), res);
let nums = vec![1, 1, 1];
let k = 1;
let res = 0;
assert_eq!(Solution::num_subarray_product_less_than_k(nums, k), res);
}
``````