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Problem	Diff	Pattern	Topics
Assign Cookies	Easy	Greedy - Two Pointers	greedyoptimizationsorting +1
Best Time to Buy and Sell Stock	Easy	Kadane's Algorithm	ArrayDynamic Programming
Best Time to Buy and Sell Stock (Greedy)	Easy	Greedy - Track Minimum	greedyoptimizationsorting +1
Best Time to Buy and Sell Stock (Single Pass)	Easy	Single Pass	data-structuretraversalmemory
Best Time to Buy and Sell Stock (Sliding Window)	Easy	Sliding Window	techniquesubarrayoptimization
Burst Balloons	Hard	Interval DP	dynamic-programminginterval-dpdivide-and-conquer
Capacity to Ship Packages Within D Days	Medium	Binary Search on Answer	binary-searchoptimizationmonotonic-function
Climbing Stairs	Easy	Linear DP	dynamic-programmingmemoizationtabulation +1
Coin Change	Medium	1D DP - Knapsack Variant	dynamic-programming1d-dplinear-dp +1
Combination Sum	Medium	Backtracking	recursionbacktrackingarrays
Container With Most Water	Medium	Two Pointers	techniquearraysoptimization
Contains Duplicate	Easy	Hashing	ArrayHash TableSorting
Critical Connections in a Network	Hard	Tarjan's Bridge Finding	graphdfstarjans-algorithm +1
Daily Temperatures	Medium	Monotonic Stack	techniquestackoptimization
Decode Ways	Medium	1D DP - Counting	dynamic-programming1d-dplinear-dp +1
Design Add and Search Words Data Structure	Medium	Class Design	javaoopclasses +1
Design HashSet	Easy	Class Design	javaoopthis +1
Design Iterator	Medium	Interface Implementation	javaoopinterfaces +1
Design Logger System	Easy	Class Design	javaoopencapsulation +1
Design Music Player	Medium	Composition	javaoopcomposition +1
Design Phone Directory	Medium	Class Design	javaoopencapsulation +1
Design Stack with Min	Medium	Interface Design	javaoopinterfaces +1
Factorial	Easy	Linear Recursion	recursioncall-stackdivide-and-conquer +1
Fibonacci Number	Easy	Binary Recursion	recursioncall-stackdivide-and-conquer +1
Fibonacci Number (Java Recursion)	Easy	Recursion	javafundamentalsrecursion +1
Find Bug: Bitwise vs Logical	Medium	Bitwise Operators	javafundamentalsoperators +1
Find Bug: Floating Point Comparison	Medium	Precision Issues	javafundamentalsdata-types +1
Find Bug: Infinite Loop	Medium	Loop Control	javafundamentalsloops +1
Find Bug: Missing Break	Medium	Switch Statement	javafundamentalscontrol-flow +1
Find Bug: Return Type	Easy	Return Statements	javafundamentalsmethods +1
Find Bug: Static Method	Medium	Static Methods	javafundamentalsmethods +1
Find Bug: Uninitialized Variable	Easy	Variable Initialization	javafundamentalsvariables +1
Find Median from Data Stream	Hard	Two Heaps	heappriority-queuedesign +1
Find Minimum in Rotated Sorted Array	Medium	Binary Search - Pivot	searchingdivide-and-conquersorted-array
First Unique Character	Easy	Frequency Count	javastringsimmutability +1
House Robber	Medium	Linear DP - Maximum Sum	dynamic-programming1d-dplinear-dp +1
House Robber II	Medium	1D DP - Circular	dynamic-programming1d-dplinear-dp +1
Implement Queue using Stacks	Easy	Queue Design	data-structurefifobfs
Implement Queue using Stacks (Java)	Easy	Class Design	javaoopconstructors +1
Implement Stack using Queues	Easy	Class Design	javaoopconstructors +1
Implement strStr()	Medium	String Matching	javastringsimmutability +1
Implement Trie (Prefix Tree)	Medium	Trie Design	trieprefix-treestring +1
Insert Interval	Medium	Interval Insertion	arrayssortinggreedy +1
Jump Game	Medium	Greedy - Reachability	greedydynamic-programmingarrays
Koko Eating Bananas	Medium	Binary Search on Answer	binary-searchoptimizationmonotonic-function
Kth Largest Element	Medium	Sorting	javaarraysutility +1
Kth Largest Element in a Stream	Medium	Min-Heap of Size K	heappriority-queuebinary-heap +2
Kth Largest Element in an Array (Heap)	Medium	Heap	sortingheappriority-queue +1
Kth Largest Element in an Array (Quickselect)	Medium	Quick Select	sortingdivide-and-conquerin-place +1
Largest Rectangle in Histogram	Hard	Monotonic Stack	stackmonotonic-stackarrays
Longest Common Prefix	Easy	String Comparison	javastringsmethods +1
Longest Common Subsequence	Medium	2D String DP	dynamic-programming2d-dpgrid-dp +1
Longest Consecutive Sequence	Medium	HashSet	hash-tablearraysunion-find
Longest Increasing Subsequence	Medium	DP + Binary Search	dynamic-programmingbinary-searchsubsequence
Longest Substring Without Repeating Characters	Medium	Sliding Window	techniquesubarrayoptimization
Maximum Subarray	Medium	Kadane's Algorithm	javaarraysdata-structure
Merge Intervals	Medium	Greedy - Interval Merge	arrayssortinggreedy +1
Merge Sorted Arrays	Easy	Two Pointers	javaarraysdata-structure
Min Stack	Medium	Stack with Auxiliary	stackdesign
Minimum Window Substring	Hard	Sliding Window + HashMap	sliding-windowhash-mapstrings +1
N-Queens	Hard	Backtracking	recursionbacktrackingmatrix
Next Greater Element II	Medium	Monotonic Stack - Circular	techniquestackoptimization
Online Stock Span	Medium	Monotonic Stack - Design	stackdesignmonotonic-stack
Partition Equal Subset Sum	Medium	0/1 Knapsack Variant	dynamic-programmingknapsacksubset-sum
Permutation in String	Medium	Fixed Sliding Window	techniquesubarrayoptimization
Permutations	Medium	Backtracking - Permutations	backtrackingrecursionpermutations
Power of Number	Easy	Recursion	javafundamentalsrecursion +1
Power of Two	Easy	Recursion / Math	recursioncall-stackdivide-and-conquer +1
Predict Output: Fall-Through	Easy	Switch Fall-Through	javafundamentalscontrol-flow +1
Predict Output: Loop Trace	Easy	Loop Tracing	javafundamentalsloops +1
Predict Output: Method Overloading	Easy	Method Overloading	javafundamentalsmethods +1
Predict Output: Narrowing Cast	Easy	Type Casting	javafundamentalstype-casting +1
Predict Output: Nested if	Medium	Nested Conditionals	javafundamentalscontrol-flow +1
Predict Output: Nested Loop	Medium	Nested Loops	javafundamentalsloops +1
Predict Output: Operator Precedence	Medium	Operator Precedence	javafundamentalsoperators +1
Predict Output: Overflow	Medium	Integer Overflow	javafundamentalsdata-types +1
Predict Output: Overflow Cast	Medium	Integer Overflow	javafundamentalstype-casting +1
Predict Output: Pass-by-Value	Medium	Pass-by-Value	javafundamentalsmethods +1
Predict Output: Reference Equality	Easy	Reference Equality	javafundamentalsreference-types +1
Predict Output: Reference Sharing	Medium	Mutable Objects	javafundamentalsreference-types +1
Predict Output: Short-Circuit	Easy	Short-Circuit Evaluation	javafundamentalsoperators +1
Predict Output: Type Conversion	Easy	Type Casting	javafundamentalsdata-types +1
Predict Output: Variable Scope	Easy	Variable Scope	javafundamentalsvariables +1
Print Formatted Table	Easy	Formatted Output	javafundamentalsio +2
Print Pattern	Easy	Pattern Printing	javafundamentalsloops +1
Product of Array Except Self	Medium	Prefix Sum	data-structuretraversalmemory
Read and Sum Numbers	Easy	Input Processing	javafundamentalsio +2
Reveal Cards In Increasing Order	Medium	Deque - Simulation	data-structuredouble-ended-queue
Reverse Array	Easy	Array Manipulation	javafundamentalsloops +1
Reverse String Recursively	Easy	Linear Recursion	recursioncall-stackdivide-and-conquer +1
Rotate Array	Medium	Array Manipulation	interviewonline-assessmenttime-management +1
Rotting Oranges	Medium	Multi-Source BFS	bfsqueuegrid +2
Search in Rotated Sorted Array	Medium	Modified Binary Search	searchingdivide-and-conquersorted-array
Sliding Window Maximum	Hard	Monotonic Deque	sliding-windowdequemonotonic-queue +1
Sliding Window Median	Hard	Two Heaps + Lazy Deletion	heapsliding-windowdesign +1
Sort an Array	Easy	Sorting	javaarraysutility +1
Sort Colors (Dutch National Flag)	Medium	Three-Way Partition	sortingdivide-and-conquerin-place +1
Split Array Largest Sum	Hard	Binary Search on Answer	binary-searchgreedydynamic-programming +1
String Compression	Medium	StringBuilder	javastringsstringbuilder +1
String to Integer (atoi)	Medium	Parsing	javastringsimmutability +1
Subarray Sum Equals K	Medium	HashMap + Prefix Sum	interviewpatternsstrategy +1
Subsets	Medium	Backtracking / Bit Manipulation	recursionbacktrackingbit-manipulation
Sum of Array Elements	Easy	Linear Recursion	recursioncall-stackdivide-and-conquer +1
Sum of Digits	Easy	Recursion	javafundamentalsrecursion +1
Task Scheduler	Medium	Greedy + Heap	heappriority-queuebinary-heap +2
Three Sum	Medium	Two Pointers + Sorting	arraystwo-pointerssorting +1
Top K Frequent Elements	Medium	Bucket Sort	sortinghashmapbucket-sort +1
Trapping Rain Water	Hard	Two Pointers / Stack	two-pointersstackdynamic-programming +1
Two Sum	Easy	Hashing	ArrayHash Table
Valid Anagram	Easy	Frequency Counting	Hash TableStringSorting
Valid Palindrome	Easy	Two Pointers	data-structuremanipulationpattern-matching
Valid Palindrome II	Easy	Two Pointers with Skip	techniquearraysoptimization
Valid Parentheses	Easy	Stack	StringStack
Word Ladder	Hard	BFS on Implicit Graph	bfsgraphstrings +2
Word Search	Medium	Backtracking on Grid	recursionbacktrackingmatrix +1