README.md

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.

Solutions (Ruby)

1. Two Pointers

# @param {Integer[]} nums
# @param {Integer} k
# @return {Integer}
def num_subarray_product_less_than_k(nums, k)
  return 0 if k < 2

  product = 1
  i = 0
  ret = 0

  (0...nums.size).each do |j|
    product *= nums[j]
    while product >= k
      product /= nums[i]
      i += 1
    end
    ret += j - i + 1
  end

  ret
end

Solutions (Rust)

1. Two Pointers

impl Solution {
    pub fn num_subarray_product_less_than_k(nums: Vec<i32>, k: i32) -> i32 {
        if k < 2 {
            return 0;
        }

        let mut product = 1;
        let mut i = 0;
        let mut ret = 0;

        for j in 0..nums.len() {
            product *= nums[j];
            while product >= k {
                product /= nums[i];
                i += 1;
            }
            ret += j - i + 1;
        }

        ret as i32
    }
}