LeetCode Collection
Could Not Solve Cleanly
Entries that explicitly say the solution did not come cleanly without hints, giving up, or outside help.
104 entries
Focused gallery for this signal, ordered by the strongest matching metric.
18.10.2026
hard1569. Number of Ways to Reorder Array to Get Same BST
Ways to permute keeping the same BST
16.10.2026
hard2916. Subarrays Distinct Element Sum of Squares II
Sum of squares of uniq numbers counts in all subarrays
12.10.2026
hard2897. Apply Operations on Array to Maximize Sum of Squares
Max sum of squares after any pairwise a=a|b, b=a&b
10.10.2026
medium2333. Minimum Sum of Squared Difference
Min sum of squared difs after adjusting each array by k
22.09.2026
hard3525. Find X Value of Array II
Queries of count subarrays product%k = x for x in 0..
24.08.2026
hard1872. Stone Game VIII
Alice maximize and Bob minimize the (A-B)
23.08.2026
medium1927. Sum Game
Alice fights Bob who tryies to equalize halfs
21.08.2026
hard3116. Kth Smallest Amount With Single Denomination Combination
Kth number in multipliers sequence of coins
13.08.2026
hard2213. Longest Substring of One Repeating Character
Queries of max repeating subarray after replacing characters
08.08.2026
medium3302. Find the Lexicographically Smallest Valid Sequence
Match subsequence with at most one difference
29.07.2026
hard3518. Smallest Palindromic Rearrangement II
K-th palindrome rearrangement
22.07.2026
hard3501. Maximize Active Section with Trade II
Queries l..r of max ones after replacing surrounding zeros in range
19.07.2026
medium1081. Smallest Subsequence of Distinct Characters
Smallest uniq-chars subsequence
17.07.2026
hard3312. Sorted GCD Pair Queries
Queries of position of gcd of every pair in a sorted order
10.07.2026
hard3534. Path Existence Queries in a Graph II
Queries of connected nodes shortest distances
03.07.2026
hard3620. Network Recovery Pathways
Max(min(paths)) in DAG
26.06.2026
hard3739. Count Subarrays With Majority Element II
Subarrays with majority element
24.06.2026
hard3700. Number of ZigZag Arrays II
Ways to make l..r zigzag sequence
23.06.2026
hard3699. Number of ZigZag Arrays I
Ways to make l..r zigzag sequence
20.06.2026
hard1840. Maximum Building Height
Max growing height with restrictions
12.06.2026
hard3559. Number of Ways to Assign Edge Weights II
Ways to color the all queries paths a..b in tree
05.06.2026
hard3753. Total Waviness of Numbers in Range II
Count hills and valleys base10 in a..b
30.05.2026
hard3161. Block Placement Queries
Queries 'can place a gap after place an obstacle'
12.05.2026
hard1665. Minimum Initial Energy to Finish Tasks
Energy for all tasks (spend, limit)
29.04.2026
hard3225. Maximum Score From Grid Operations
Max sum adjacent to marked columns
25.04.2026
hard3464. Maximize the Distance Between Points on a Square
Max of minimum distnace between selected k points on square perimeter
23.04.2026
medium2615. Sum of Distances
Sum of distances to each occurance
14.04.2026
hard2463. Minimum Total Distance Traveled
Shortest distances to travel robots to factories
09.04.2026
hard3655. XOR After Range Multiplication Queries II
Run stepped multiplication queries
03.04.2026
hard3661. Maximum Walls Destroyed by Robots
Max walls hit, each robot shoot left or right
31.03.2026
hard3474. Lexicographically Smallest Generated String
String from pattern matches
26.03.2026
hard3548. Equal Sum Grid Partition II
Cut matrix in half sums, can remove one cell
09.03.2026
medium3129. Find All Possible Stable Binary Arrays I
Count 01-arrays with z zeros, o ones, at most l repeat
27.02.2026
hard3666. Minimum Operations to Equalize Binary String
Min steps to convert 01 stirng to ones flipping K
20.02.2026
hard761. Special Binary String
Swaps of 1M0-special substring to make string large
13.02.2026
medium3714. Longest Balanced Substring II
Largest equal frequencies substring of abc-string
11.02.2026
hard3721. Longest Balanced Subarray II
Max subarray evens count = odds count tree
02.02.2026
hard3013. Divide an Array Into Subarrays With Minimum Cost II
Min sum of k splits at max d distance window
30.01.2026
hard2977. Minimum Cost to Convert String II
Min cost to convert string with transitions of substrings
28.01.2026
hard3651. Minimum Cost Path with Teleportations
Min cost to walk 2D grid with free teleports
23.01.2026
hard3510. Minimum Pair Removal to Sort Array II
Sort by removing min-sum pairs
14.01.2026
hard3454. Separate Squares II
Min y to equal split areas exclude intersections sweep
13.01.2026
medium3453. Separate Squares I
Min Y to split into equal areas
06.12.2025
medium3578. Count Partitions With Max-Min Difference at Most K
Ways to partition into parts (max-min) at most k queue
08.11.2025
hard1611. Minimum One Bit Operations to Make Integers Zero
Min steps to make zero by xor 1 or xor rightmost+1
21.10.2025
medium3346. Maximum Frequency of an Element After Performing Operations I
Max frequency after changing +k..-k ops elements window
17.10.2025
medium3003. Maximize the Number of Partitions After Operations
Max k-uniq parts after changing one letter
12.10.2025
medium3539. Find Sum of Array Product of Magical Sequences
Product of all good subsequences and permutations
24.09.2025
medium166. Fraction to Recurring Decimal
Calc a/b to string x.y(z)
06.09.2025
hard3495. Minimum Operations to Make Array Elements Zero
Sum query [a..b] of optimal pairwise /4 until range is zero
05.09.2025
medium2749. Minimum Operations to Make the Integer Zero
Min ops to subtract n2+2^(0..60) from n1 and make n1=0
17.08.2025
medium837. New 21 Game
Probability sum of random(1..m) less than n when stop adding at k
2.08.2025
hard2561. Rearranging Fruits
Min swaps cost to make a==b
26.07.2025
hard3480. Maximize Subarrays After Removing One Conflicting Pair
Max subarrays count without excluded pairs-1 sweep
24.07.2025
hard2322. Minimum Score After Removals on a Tree
Min(max group xor - min group xor) by removing 2 edges from tree
17.07.2025
medium3202. Find the Maximum Length of Valid Subsequence II
Longest same-pair-k-parity subsequence
12.07.2025
hard1900. The Earliest and Latest Rounds Where Players Compete
First and last round Alice fight Bob
2.07.2025
hard3333. Find the Original Typed String II
ways to remove duplicates, preserve length at least k
26.06.2025
medium2311. Longest Binary Subsequence Less Than or Equal to K
Longest binary subsequence less than K
17.06.2025
hard3405. Count the Number of Arrays with K Matching Adjacent Elements
Combinations k equal siblings 1..m in [n] array
13.06.2025
medium2616. Minimize the Maximum Difference of Pairs
Min max diffs non-overlapped pairs search
11.06.2025
hard3445. Maximum Difference Between Even and Odd Frequency II
Max odd - min even frequency, window at least k
09.06.2025
hard440. K-th Smallest in Lexicographical Order
k-th lexicographical number of 1..n
01.06.2025
medium2929. Distribute Candies Among Children II
Ways to give limited from n candies to 3 kids
23.05.2025
hard3068. Find the Maximum Sum of Node Values
Max sum by k-xoring edges
22.05.2025
medium3362. Zero Array Transformation III
Max removed queries still zero-fy an array
14.05.2025
hard3337. Total Characters in String After Transformations II
t steps to convert char into next nums[c] chars
09.05.2025
hard3343. Count Number of Balanced Permutations
Permutations of even-odd position sums equal
01.05.2025
hard2071. Maximum Number of Tasks You Can Assign
Tasks can be done by workers with pills search
25.04.2025
medium2845. Count of Interesting Subarrays
Subarrays, count a[i]%m=k is c%m=k map
22.04.2025
hard2338. Count the Number of Ideal Arrays
Arrays a[i] % a[i - 1] == 0, i..n, a[i]..max
15.04.2025
hard2179. Count Good Triplets in an Array
Triplets in same order in both (0..n)-arrays
14.04.2025
easy1534. Count Good Triplets
Triplets with diff less than a,b,c
29.03.2025
hard2818. Apply Operations to Maximize Score
Multiply k numbers with max prime factor count stack
26.03.2025
medium2033. Minimum Operations to Make a Uni-Value Grid
Min sum of differences of x times
16.03.2025
medium2594. Minimum Time to Repair Cars
Min rank[i] count^2 to fix all cars search
13.03.2025
medium3356. Zero Array Transformation II
Min queries (l..r, v) to decrease nums by v to 0 sweep
25.02.2025
medium1524. Number of Sub-arrays With Odd Sum
Count odd sum subarrays sum
09.02.2025
medium2364. Count Number of Bad Pairs
Count pairs a[i] - a[j] != j - i
30.01.2025
hard2493. Divide Nodes Into the Maximum Number of Groups
Max count of bipartitions in a graph
26.01.2025
hard2127. Maximum Employees to Be Invited to a Meeting
Max connected siblings in graph
19.01.2025
hard407. Trapping Rain Water II
Trap the water in 2D height matrix
12.01.2025
medium2116. Check if a Parentheses String Can Be Valid
Balance parenthesis with wildcards
28.12.2024
hard689. Maximum Sum of 3 Non-Overlapping Subarrays
max non-intersecting intervals programming window
24.12.2024
hard3203. Find Minimum Diameter After Merging Two Trees
Diameter of 2 connected trees
23.12.2024
medium2471. Minimum Number of Operations to Sort a Binary Tree by Level
Min swaps to sort tree layers
22.12.2024
hard2940. Find Building Where Alice and Bob Can Meet
Common indices t, h[t] > h[a], h[t] > h[b] for queries q[][a,b] stack
21.12.2024
hard2872. Maximum Number of K-Divisible Components
Max connected components divisible by k in graph
15.12.2024
medium1792. Maximum Average Pass Ratio
Arrange passed students to improve average score
07.12.2024
medium1760. Minimum Limit of Balls in a Bag
Max number after at most maxOperations of splitting search
15.11.2024
medium1574. Shortest Subarray to be Removed to Make Array Sorted
Min subarray remove to make array sorted pointers
31.10.2024
hard2463. Minimum Total Distance Traveled
Min robots[x] travel to factories[x,capacity] programming
03.10.2024
medium1590. Make Sum Divisible by P
Min removed subarray length to make remainder % p = 0
15.09.2024
medium1371. Find the Longest Substring Containing Vowels in Even Counts
Longest substring with even number of "aeiou" manipulation pointers
30.08.2024
hard2699. Modify Graph Edge Weights
Assign vacant -1 weight in graph to make shorted path equal target
21.07.2024
hard2392. Build a Matrix With Conditions
Build a matrix from a graph conditions
31.05.2024
medium260. Single Number III
Two not duplicated numbers from array manipulation
19.05.2024
hard3068. Find the Maximum Sum of Node Values
Max sum after xor k any edges in a tree
23.04.2024
medium310. Minimum Height Trees
Center of an acyclic graph
23.03.2024
medium143. Reorder List
Reorder Linked List 1->2->3->4->5 -> 1->5->2->4->3
22.03.2024
easy234. Palindrome Linked List
Is Linked List a palindrome
09.02.2024
medium368. Largest Divisible Subset
Longest subset of divisible by s[i] % s[j] == 0 || s[j] % s[i] == 0.
22.01.2024
easy645. Set Mismatch
Return missing and duplicated number in 1..n array with one number replaced.
30.07.2023
hard664. Strange Printer
Minimum continuous overrides by the same character to make a string