LeetCode Library
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Start with a year, a language, or one of the recurring patterns.
Years
Languages
Patterns
- Array373
- Graph211
- String204
- Sorting153
- Dynamic Programming97
- Simulation97
- Tree95
- Binary Search80
- Math75
- Bit Manipulation74
- Hash Map65
- Two Pointers61
- Stack52
- Sliding Window51
- Heap44
- Backtracking37
- Linked List36
- Greedy32
- Union Find31
- Queue27
- Prefix Sum20
- Trie17
- Intervals15
- Monotonic Stack13
Archive
Newest first. Start broad, then filter down. Each entry opens the full post for that day.
24.04.2026
easy2833. Furthest Point From Origin
Max dist when replace with L or R
23.04.2026
medium2615. Sum of Distances
Sum of distances to each occurance
22.04.2026
medium2452. Words Within Two Edits of Dictionary
Words in dictionary with 2 edits
21.04.2026
medium1722. Minimize Hamming Distance After Swap Operations
Diff src vs target after rearrange by rules
20.04.2026
easy2078. Two Furthest Houses With Different Colors
Max distance between different numbers
19.04.2026
medium1855. Maximum Distance Between a Pair of Values
Max distance a[i] not greater than b[j] window
18.04.2026
easy3783. Mirror Distance of an Integer
Diff with reversal
17.04.2026
medium3761. Minimum Absolute Distance Between Mirror Pairs
Distance to prev mirror number
16.04.2026
medium3488. Closest Equal Element Queries
Shortest distances to the same values
15.04.2026
easy2515. Shortest Distance to Target String in a Circular Array
Distance to target
14.04.2026
hard2463. Minimum Total Distance Traveled
Shortest distances to travel robots to factories
13.04.2026
easy1848. Minimum Distance to the Target Element
Distance to target from start
12.04.2026
hard1320. Minimum Distance to Type a Word Using Two Fingers
Min travel on keyboard to type a word
11.04.2026
medium3741. Minimum Distance Between Three Equal Elements II
Min sum of distances between i,j,k of the same values
10.04.2026
easy3740. Minimum Distance Between Three Equal Elements I
Min sum of distances between i,j,k of the same values
09.04.2026
hard3655. XOR After Range Multiplication Queries II
Run stepped multiplication queries
08.04.2026
medium3653. XOR After Range Multiplication Queries I
Run queries
07.04.2026
medium2069. Walking Robot Simulation II
Implement perimeter-robot
06.04.2026
medium874. Walking Robot Simulation
Farthest robot movement
05.04.2026
easy657. Robot Return to Origin
R,L,U,D return to 0 in XY plane
04.04.2026
medium2075. Decode the Slanted Ciphertext
Decode row-encoded string
03.04.2026
hard3661. Maximum Walls Destroyed by Robots
Max walls hit, each robot shoot left or right
02.04.2026
medium3418. Maximum Amount of Money Robot Can Earn
Max sum path, 2 skips allowed
01.04.2026
hard2751. Robot Collisions
Collide LR robots
31.03.2026
hard3474. Lexicographically Smallest Generated String
String from pattern matches
30.03.2026
medium2840. Check if Strings Can be Made Equal With Operations II
Strings equal at odd-even positions
29.03.2026
easy2839. Check if Strings Can be Made Equal With Operations I
Match a and b at (0|2,1|3) positions
28.03.2026
hard2573. Find the String with LCP
Build string from longest common prefixes matrix
27.03.2026
easy2946. Matrix Similarity After Cyclic Shifts
Shift rows k times left and right
26.03.2026
hard3548. Equal Sum Grid Partition II
Cut matrix in half sums, can remove one cell
25.03.2026
medium3546. Equal Sum Grid Partition I
Split matrix to equal sums
24.03.2026
medium2906. Construct Product Matrix
Product of other cells in a matrix
23.03.2026
medium1594. Maximum Non Negative Product in a Matrix
Max product path right-down
22.03.2026
easy1886. Determine Whether Matrix Can Be Obtained By Rotation
Rotate matrix
21.03.2026
medium3643. Flip Square Submatrix Vertically
Reverse submatrix k by k
20.03.2026
medium3567. Minimum Absolute Difference in Sliding Submatrix
Mid diffs in k k submatrices
19.03.2026
medium3212. Count Submatrices With Equal Frequency of X and Y
Count prefix freq X == freq Y
18.03.2026
medium3070. Count Submatrices with Top-Left Element and Sum Less Than k
Count prefix sums less than K
17.03.2026
medium1727. Largest Submatrix With Rearrangements
Max area of binary matrix, swap columns
16.03.2026
medium1878. Get Biggest Three Rhombus Sums in a Grid
Top 3 rhombus sums
15.03.2026
hard1622. Fancy Sequence
Design: add number, mulriply all, add all
14.03.2026
medium1415. The k-th Lexicographical String of All Happy Strings of Length n
K-th generated abc non-repeating string
13.03.2026
medium3296. Minimum Number of Seconds to Make Mountain Height Zero
Min steps to work a mountain with arithmetic-sum-workers
12.03.2026
hard3600. Maximize Spanning Tree Stability with Upgrades
Max of min values in span tree of graph, 2 s at most k
11.03.2026
easy1009. Complement of Base 10 Integer
Invert binary
10.03.2026
hard3130. Find All Possible Stable Binary Arrays II
array to make with z zeros, o ones, l repeats
09.03.2026
medium3129. Find All Possible Stable Binary Arrays I
Count 01-arrays with z zeros, o ones, at most l repeat
08.03.2026
medium1980. Find Unique Binary String
Uniq bits not in a set
07.03.2026
medium1888. Minimum Number of Flips to Make the Binary String Alternating
Min flips to make 01 alterating string sum window
06.03.2026
easy1784. Check if Binary String Has at Most One Segment of Ones
+0 pattern
05.03.2026
easy1758. Minimum Changes To Make Alternating Binary String
Min flips to make bits alterating
04.08.2026
easy1582. Special Positions in a Binary Matrix
Count single 1-row-column
03.03.2026
medium1545. Find Kth Bit in Nth Binary String
Kth bit in s=s+1+inv(rev(s)) sequence
02.03.2026
medium1536. Minimum Swaps to Arrange a Binary Grid
Min rows swaps to zero above diagonal
01.03.2026
medium1689. Partitioning Into Minimum Number Of Deci-Binary Numbers
Min 01-strings add up to target
28.02.2026
medium1680. Concatenation of Consecutive Binary Numbers
Concat binaries 1..n
27.02.2026
hard3666. Minimum Operations to Equalize Binary String
Min steps to convert 01 stirng to ones flipping K
26.02.2026
medium1404. Number of Steps to Reduce a Number in Binary Representation to One
Ops /2+1 to make 1
25.02.2026
easy1356. Sort Integers by The Number of 1 Bits
Sort
24.02.2026
easy1022. Sum of Root To Leaf Binary Numbers
Sum of a binary numbers in a binary tree
23.02.2026
medium1461. Check If a String Contains All Binary Codes of Size K
All numbers as substring length of k window
22.02.2026
easy868. Binary Gap
Distance between onces in a binary
21.02.2026
easy762. Prime Number of Set Bits in Binary Representation
Number in l..r with prime bits count
20.02.2026
hard761. Special Binary String
Swaps of 1M0-special substring to make string large
19.02.2026
easy696. Count Binary Substrings
Count substrings of 01 and 10 window
18.02.2026
easy693. Binary Number with Alternating Bits
Alternating bits
17.02.2026
easy401. Binary Watch
All times with count bits set
16.02.2026
easy190. Reverse Bits
Reverse bits
15.02.2026
easy67. Add Binary
Binary strings sum
14.02.2026
medium799. Champagne Tower
Flow in a Pascal's Triangle
13.02.2026
medium3714. Longest Balanced Substring II
Largest equal frequencies substring of abc-string
12.02.2026
medium3713. Longest Balanced Substring I
Max substring with equal frequencies window
11.02.2026
hard3721. Longest Balanced Subarray II
Max subarray evens count = odds count tree
10.02.2026
medium3719. Longest Balanced Subarray I
Longes even=odd subarray
09.02.2026
medium1382. Balance a Binary Search Tree
Balance binary search tree
08.02.2026
easy110. Balanced Binary Tree
Is tree balanced?
07.02.2026
medium1653. Minimum Deletions to Make String Balanced
Min removal to balance 'ab'
06.02.2026
medium3634. Minimum Removals to Balance Array
Min removals to make min k not less than max window
05.02.2026
easy3379. Transformed Array
Shuffled list i+n[i]
03.02.2026
easy3637. Trionic Array I
Validate inc,dec,inc sequency
02.02.2026
hard3013. Divide an Array Into Subarrays With Minimum Cost II
Min sum of k splits at max d distance window
01.02.2026
easy3010. Divide an Array Into Subarrays With Minimum Cost I
Split on 2 min values
31.01.2026
easy744. Find Smallest Letter Greater Than Target
Larger letter in array
30.01.2026
hard2977. Minimum Cost to Convert String II
Min cost to convert string with transitions of substrings
29.01.2026
medium2976. Minimum Cost to Convert String I
Min cost to convert string
28.01.2026
hard3651. Minimum Cost Path with Teleportations
Min cost to walk 2D grid with free teleports
27.01.2026
medium3650. Minimum Cost Path with Edge Reversals
Min path in weighted graph with reverse 2w nodes
26.01.2026
easy1200. Minimum Absolute Difference
Min diff pairs
25.01.2026
easy1984. Minimum Difference Between Highest and Lowest of K Scores
Min k-diff window
24.01.2026
medium1877. Minimize Maximum Pair Sum in Array
Min max pair
23.01.2026
hard3510. Minimum Pair Removal to Sort Array II
Sort by removing min-sum pairs
22.01.2026
easy3507. Minimum Pair Removal to Sort Array I
Sort by removing lowest sum pairs
21.01.2026
medium3315. Construct the Minimum Bitwise Array II
Reverse operation x or (x+1)
20.01.2026
easy3314. Construct the Minimum Bitwise Array I
Reverse x | (x+1) operation on prime numbers
19.01.2025
medium1292. Maximum Side Length of a Square with Sum Less than or Equal to Threshold
Max square with sum less than threshold
18.01.2026
medium1895. Largest Magic Square
Max magic square
17.01.2026
medium3047. Find the Largest Area of Square Inside Two Rectangles
Max square in intersection
16.01.2026
medium2975. Maximum Square Area by Removing Fences From a Field
Max square after remove vertical or horizontal bars
15.01.2026
medium2943. Maximize Area of Square Hole in Grid
Max square area after removing bars in a grid
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
12.01.2026
easy1266. Minimum Time Visiting All Points
Euclid travel distance
11.01.2026
hard85. Maximal Rectangle
Max all-1 rectangle in 2D matrix stack
10.01.2026
medium712. Minimum ASCII Delete Sum for Two Strings
Min removed sum to make strings equal
09.01.2026
medium865. Smallest Subtree with all the Deepest Nodes
Lowest common ancestor of the deepest nodes
08.01.2026
hard1458. Max Dot Product of Two Subsequences
Max product of 2 subsequencies
07.01.2026
medium1339. Maximum Product of Splitted Binary Tree
Max sumA sumB of a tree split
06.01.2026
medium1161. Maximum Level Sum of a Binary Tree
Min level max sum in tree
05.01.2026
medium1975. Maximum Matrix Sum
Max sum after multiply -1 adjacent cells
04.12.2025
medium1390. Four Divisors
Sum of exactly four-divisors of each number
03.12.2026
hard1411. Number of Ways to Paint N × 3 Grid
Ways to color 3xN grid
02.01.2026
easy961. N-Repeated Element in Size 2N Array
Duplicate majority element
01.01.2026
easy66. Plus One
Increment big number
31.12.2025
hard1970. Last Day Where You Can Still Cross
Last day top connected to bottom in 2D matrix
30.12.2025
medium840. Magic Squares In Grid
Count 'magic' 3x3 squares
29.12.2025
medium756. Pyramid Transition Matrix
Can build a pyramid from transitions?
28.12.2025
easy1351. Count Negative Numbers in a Sorted Matrix
Count negatives in 2D sorted matrix
27.12.2025
hard2402. Meeting Rooms III
Most frequent room 0..n for meetings [s,e]
26.12.2025
medium2483. Minimum Penalty for a Shop
Min close time by customers max volune
25.12.2025
medium3075. Maximize Happiness of Selected Children
K max values, decreas each pick
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