https://leetcode.com/problems/count-the-number-of-ideal-arrays/description/


Arrays a[i] % a[i - 1] == 0, i..n, a[i]..max #hard #combinatorics

# 17.06.2025
[3405. Count the Number of Arrays with K Matching Adjacent Elements](https://leetcode.com/problems/count-the-number-of-arrays-with-k-matching-adjacent-elements/description/) hard


Combinations k equal siblings 1..m in [n] array #hard #combinatorics #math

# 05.10.2025
[3539. Find Sum of Array Product of Magical Sequences](https://leetcode.com/problems/find-sum-of-array-product-of-magical-sequences/description/) medium


Product of all good subsequences and permutations #hard #combinatorics