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

https://leetcode.com/problems/count-subarrays-with-fixed-bounds/description


Subarrays with min=minK, max=maxK #hard #two_pointers

https://leetcode.com/problems/count-subarrays-with-score-less-than-k/description/

Subarrays sum * cnt <= k #hard #two_pointers

Tasks can be done by workers with pills #hard #binary_search


https://leetcode.com/problems/maximum-number-of-tasks-you-can-assign/description

Permutations of even-odd position sums equal #hard #dp #math


https://leetcode.com/problems/count-number-of-balanced-permutations/description/

t steps to convert char into next nums[c] chars #hard #dp #math


https://leetcode.com/problems/total-characters-in-string-after-transformations-ii/description

https://leetcode.com/problems/painting-a-grid-with-three-different-colors/description


Ways to 3-color m*n grid, no adjucents #hard #dp #matrix

https://leetcode.com/problems/find-the-maximum-sum-of-node-values/description/

Max sum by k-xoring edges #hard #tree #dp

https://leetcode.com/problems/largest-color-value-in-a-directed-graph/description/


Max color freq path #hard #dp #toposort

Max even-edged siblings after merging trees #hard #graph


https://leetcode.com/problems/maximize-the-number-of-target-nodes-after-connecting-trees-ii/description

https://leetcode.com/problems/candy/description/

Min candies, fair siblings by ratings #hard #greedy

https://leetcode.com/problems/maximum-candies-you-can-get-from-boxes/description


Open boxes graph with keys simulation #hard

# 09.06.2025
[440. K-th Smallest in Lexicographical Order](https://leetcode.com/problems/k-th-smallest-in-lexicographical-order/description/) hard

k-th lexicographical number of 1..n #hard

# 11.06.2025
[3445. Maximum Difference Between Even and Odd Frequency II](https://leetcode.com/problems/maximum-difference-between-even-and-odd-frequency-ii/description) hard

Max odd - min even frequency, window at least k #hard

# 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

# 23.06.2025
[2081. Sum of k-Mirror Numbers](https://leetcode.com/problems/sum-of-k-mirror-numbers/description) hard


n palindromes in both 10 and k-base #hard #math

# 25.06.2025
[2040. Kth Smallest Product of Two Sorted Arrays](https://leetcode.com/problems/kth-smallest-product-of-two-sorted-arrays/description/) hard



K-th increasing product from two arrays #hard #binary_search