Problems
130 problems#1
Two Sum⭐ must
Arrays / HashingAmazonGoogleStripe
Easy
#242
Valid Anagram⭐ must🔒
Arrays / HashingAmazon
Easy
#121
Best Time to Buy and Sell Stock⭐ must🔒
Sliding WindowAmazonFacebook
Easy
#20
Valid Parentheses⭐ must🔒
StackAmazonGoogleFacebook
Easy
#21
Merge Two Sorted Lists⭐ must🔒
Linked ListAmazonGoogle
Easy
125 more problems locked
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#206
Reverse Linked List⭐ must
Linked ListAmazonGoogleFacebook
Easy
#572
Subtree of Another Tree⭐ must
TreesAmazonFacebook
Easy
#217
Contains Duplicate
Arrays / HashingAmazon
Easy
#125
Valid Palindrome
Two PointersFacebook
Easy
#392
Is Subsequence
Two PointersGoogle
Easy
#680
Valid Palindrome II
Two PointersFacebook
Easy
#977
Squares of a Sorted Array
Two PointersGoogle
Easy
#643
Maximum Average Subarray I
Sliding WindowGoogle
Easy
#704
Binary Search
Binary SearchGoogle
Easy
#141
Linked List Cycle
Linked ListAmazon
Easy
#104
Maximum Depth of Binary Tree
TreesAmazonFacebook
Easy
#100
Same Tree
TreesAmazon
Easy
#226
Invert Binary Tree
TreesGoogleAmazon
Easy
#110
Balanced Binary Tree
TreesAmazon
Easy
#543
Diameter of Binary Tree
TreesAmazonFacebook
Easy
#703
Kth Largest Element in a Stream
Heap / Priority QueueAmazon
Easy
#1046
Last Stone Weight
Heap / Priority QueueGoogle
Easy
#252
Meeting Rooms
IntervalsFacebook
Easy
#70
Climbing Stairs
Dynamic ProgrammingAmazon
Easy
#191
Number of 1 Bits
Math & Bit ManipulationMicrosoft
Easy
#338
Counting Bits
Math & Bit ManipulationMicrosoft
Easy
#268
Missing Number
Math & Bit ManipulationAmazonGoogle
Easy
#49
Group Anagrams⭐ must
Arrays / HashingAmazonGoogle
Medium
#128
Longest Consecutive Sequence⭐ must
Arrays / HashingGoogleAmazon
Medium
#238
Product of Array Except Self⭐ must
Arrays / HashingAmazonFacebook
Medium
#347
Top K Frequent Elements⭐ must
Arrays / HashingAmazonFacebook
Medium
#15
3Sum⭐ must
Two PointersAmazonFacebook
Medium
#11
Container With Most Water⭐ must
Two PointersAmazonGoogle
Medium
#3
Longest Substring Without Repeating Characters⭐ must
Sliding WindowAmazonGoogleFacebook
Medium
#155
Min Stack⭐ must
StackAmazon
Medium
#739
Daily Temperatures⭐ must
StackAmazonGoogle
Medium
#153
Find Minimum in Rotated Sorted Array⭐ must
Binary SearchAmazonGoogle
Medium
#33
Search in Rotated Sorted Array⭐ must
Binary SearchAmazonFacebook
Medium
#102
Binary Tree Level Order Traversal⭐ must
TreesAmazonGoogle
Medium
#98
Validate Binary Search Tree⭐ must
TreesAmazonFacebook
Medium
#621
Task Scheduler⭐ must
Heap / Priority QueueAmazonGoogle
Medium
#56
Merge Intervals⭐ must
IntervalsAmazonGoogleFacebook
Medium
#200
Number of Islands⭐ must
GraphsAmazonGoogleFacebook
Medium
#207
Course Schedule⭐ must
GraphsAmazonGoogle
Medium
#417
Pacific Atlantic Water Flow⭐ must
GraphsGoogle
Medium
#198
House Robber⭐ must
Dynamic ProgrammingAmazonGoogle
Medium
#322
Coin Change⭐ must
Dynamic ProgrammingAmazonGoogle
Medium
#300
Longest Increasing Subsequence⭐ must
Dynamic ProgrammingAmazonGoogle
Medium
#72
Edit Distance⭐ must
Dynamic ProgrammingAmazonGoogle
Medium
#39
Combination Sum⭐ must
BacktrackingAmazonGoogle
Medium
#36
Valid Sudoku
Arrays / HashingAmazon
Medium
#380
Insert Delete GetRandom O(1)
Arrays / HashingFacebookAmazon
Medium
#560
Subarray Sum Equals K
Arrays / HashingFacebookAmazon
Medium
#525
Contiguous Array
Arrays / HashingFacebook
Medium
#167
Two Sum II Input Array Is Sorted
Two PointersAmazon
Medium
#424
Longest Repeating Character Replacement
Sliding WindowGoogle
Medium
#567
Permutation in String
Sliding WindowAmazon
Medium
#1004
Max Consecutive Ones III
Sliding WindowAmazon
Medium
#904
Fruit Into Baskets
Sliding WindowGoogle
Medium
#150
Evaluate Reverse Polish Notation
StackAmazon
Medium
#394
Decode String
StackGoogle
Medium
#735
Asteroid Collision
StackAmazon
Medium
#853
Car Fleet
StackGoogle
Medium
#74
Search a 2D Matrix
Binary SearchAmazon
Medium
#875
Koko Eating Bananas
Binary SearchFacebook
Medium
#981
Time Based Key-Value Store
Binary SearchGoogle
Medium
#162
Find Peak Element
Binary SearchFacebook
Medium
#142
Linked List Cycle II
Linked ListAmazon
Medium
#143
Reorder List
Linked ListAmazon
Medium
#19
Remove Nth Node From End of List
Linked ListAmazonGoogle
Medium
#138
Copy List with Random Pointer
Linked ListAmazon
Medium
#235
Lowest Common Ancestor of a Binary Search Tree
TreesAmazonFacebook
Medium
#230
Kth Smallest Element in a BST
TreesAmazon
Medium
#199
Binary Tree Right Side View
TreesFacebookAmazon
Medium
#105
Construct Binary Tree from Preorder and Inorder Traversal
TreesAmazonGoogle
Medium
#337
House Robber III
TreesAmazon
Medium
#215
Kth Largest Element in an Array
Heap / Priority QueueAmazonFacebook
Medium
#355
Design Twitter
Heap / Priority QueueAmazon
Medium
#373
Find K Pairs with Smallest Sums
Heap / Priority QueueAmazon
Medium
#57
Insert Interval
IntervalsGoogle
Medium
#435
Non-overlapping Intervals
IntervalsGoogle
Medium
#986
Interval List Intersections
IntervalsFacebook
Medium
#253
Meeting Rooms II
IntervalsFacebookGoogle
Medium
#695
Max Area of Island
GraphsAmazonGoogle
Medium
#994
Rotting Oranges
GraphsAmazon
Medium
#130
Surrounded Regions
GraphsAmazon
Medium
#133
Clone Graph
GraphsFacebookAmazon
Medium
#210
Course Schedule II
GraphsAmazon
Medium
#684
Redundant Connection
GraphsAmazon
Medium
#323
Number of Connected Components in an Undirected Graph
GraphsLinkedIn
Medium
#261
Graph Valid Tree
GraphsGoogleLinkedIn
Medium
#213
House Robber II
Dynamic ProgrammingAmazon
Medium
#5
Longest Palindromic Substring
Dynamic ProgrammingAmazonGoogle
Medium
#62
Unique Paths
Dynamic ProgrammingAmazonGoogle
Medium
#1143
Longest Common Subsequence
Dynamic ProgrammingAmazonGoogle
Medium
#518
Coin Change 2
Dynamic ProgrammingAmazon
Medium
#416
Partition Equal Subset Sum
Dynamic ProgrammingAmazonFacebook
Medium
#152
Maximum Product Subarray
Dynamic ProgrammingAmazonLinkedIn
Medium
#91
Decode Ways
Dynamic ProgrammingFacebookAmazon
Medium
#139
Word Break
Dynamic ProgrammingGoogleAmazonFacebook
Medium
#309
Best Time to Buy and Sell Stock with Cooldown
Dynamic ProgrammingAmazon
Medium
#494
Target Sum
Dynamic ProgrammingFacebookAmazon
Medium
#40
Combination Sum II
BacktrackingAmazon
Medium
#46
Permutations
BacktrackingAmazonGoogle
Medium
#78
Subsets
BacktrackingAmazonFacebook
Medium
#90
Subsets II
BacktrackingAmazon
Medium
#79
Word Search
BacktrackingAmazonGoogleFacebook
Medium
#131
Palindrome Partitioning
BacktrackingAmazonGoogle
Medium
#208
Implement Trie Prefix Tree
TriesAmazonGoogle
Medium
#211
Design Add and Search Words Data Structure
TriesFacebook
Medium
#421
Maximum XOR of Two Numbers in an Array
TriesGoogle
Medium
#648
Replace Words
TriesGoogle
Medium
#371
Sum of Two Integers
Math & Bit ManipulationAmazon
Medium
#7
Reverse Integer
Math & Bit ManipulationAmazon
Medium
#42
Trapping Rain Water⭐ must
Two PointersAmazonGoogleFacebook
Hard
#76
Minimum Window Substring⭐ must
Sliding WindowFacebookAmazon
Hard
#84
Largest Rectangle in Histogram⭐ must
StackAmazonGoogle
Hard
#4
Median of Two Sorted Arrays⭐ must
Binary SearchGoogleAmazon
Hard
#23
Merge k Sorted Lists⭐ must
Linked ListAmazonGoogle
Hard
#124
Binary Tree Maximum Path Sum⭐ must
TreesAmazonFacebook
Hard
#297
Serialize and Deserialize Binary Tree⭐ must
TreesFacebookAmazon
Hard
#295
Find Median from Data Stream⭐ must
Heap / Priority QueueAmazonGoogle
Hard
#127
Word Ladder⭐ must
GraphsAmazonGoogle
Hard
#212
Word Search II⭐ must
TriesAmazonGoogle
Hard
#41
First Missing Positive
Arrays / HashingAmazon
Hard
#239
Sliding Window Maximum
Sliding WindowAmazonGoogle
Hard
#25
Reverse Nodes in k-Group
Linked ListAmazon
Hard
#97
Interleaving String
Dynamic ProgrammingGoogle
Hard
#312
Burst Balloons
Dynamic ProgrammingGoogle
Hard
#51
N-Queens
BacktrackingAmazonGoogle
Hard