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A practical DSA collection designed around problem solving, patterns and interview preparation.

284Problems
14Topics
StructuredLearning
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14 sections

Problem Explorer

284

Practice in sequence.

01
Kadane's Algorithm / Maximum Subarray
Arrays
LC
02
Majority Element
Arrays
LC
03
Best Time to Buy and Sell Stock
DP
LC
04
Coin Change
DP
LC
05
Edit Distance
DP
LC
06
Search in Rotated Sorted Array
Searching & Sorting
LC
07
Maximum Product Subarray
Arrays
LC
08
Trapping Rain Water
Arrays
LC
09
Word Break
BONUS
LC
10
Number of Islands
Graphs
LC
11
Median of Two Sorted Arrays
Searching & Sorting
LC
12
Longest Common Prefix
Strings
LC
13
Longest Palindromic Substring
Strings
LC
14
Container With Most Water
Arrays
LC
15
Two Sum
Arrays
LC
16
Lru Cache
Linked List
LC
17
Find Median From Data Stream
Heaps & Hashing
LC
18
Kth Largest Element in an Array
Heaps & Hashing
LC
19
Remove Invalid Parentheses
BONUS
LC
20
Longest Increasing Subsequence
DP
LC
21
Cheapest Flights Within K Stops
Graphs
LC
22
Swim In Rising Water
Graphs
LC
23
Word Ladder
Graphs
LC
24
Binary Search
Searching & Sorting
LC
25
Split Array Largest Sum
Searching & Sorting
LC
26
First Missing Positive
Arrays
LC
27
Merge Intervals
Arrays
LC
28
Next Permutation
Arrays
LC
29
Rotate Image
Arrays
LC
30
Squares Of A Sorted Array
Arrays
LC
31
Word Search
Arrays
LC
32
Longest Substring Without Repeating Characters
Strings
LC
33
Minimum Window Substring
Strings
LC
34
Palindromic Substrings
Strings
LC
35
Recover Binary Search Tree
Binary Trees
LC
36
Serialize And Deserialize Binary Tree
Binary Trees
LC
37
Combination Sum
BONUS
LC
38
Burst Balloons
DP
LC
39
Frog Jump
DP
LC
40
Regular Expression Matching
DP
LC
41
Number Of Operations To Make Network Connected
Graphs
LC
42
Redundant Connection
Graphs
LC
43
Regions Cut By Slashes
Graphs
LC
44
Rotting Oranges
Graphs
LC
45
Insert Delete Getrandom O(1)
Heaps & Hashing
LC
46
Reverse Integer
BONUS
LC
47
Capacity To Ship Packages Within D Days
Searching & Sorting
LC
48
Find Peak Element
Searching & Sorting
LC
49
Powx N
Searching & Sorting
LC
50
3Sum
Arrays
LC
51
Best Time to Buy and Sell Stock II
Arrays
LC
52
Fibonacci Number
Arrays
LC
53
Find the Duplicate Number
Arrays
LC
54
Jump Game
Arrays
LC
55
Multiply Strings
Arrays
LC
56
Partition Labels
Arrays
LC
57
Pascals Triangle
Arrays
LC
58
Product of Array Except Self
Arrays
LC
59
Remove Duplicates From Sorted Array
Arrays
LC
60
Spiral Matrix
Arrays
LC
61
Subarray Sum Equals K
Arrays
LC
62
The Skyline Problem
Arrays
LC
63
Group Anagrams
Strings
LC
64
Longest Repeating Character Replacement
Strings
LC
65
Merge K Sorted Lists
Linked List
LC
66
Backspace String Compare
Stacks & Queues
LC
67
Daily Temperatures
Stacks & Queues
LC
68
Gas Station
Stacks & Queues
LC
69
Implement Stack Using Queues
Stacks & Queues
LC
70
Min Stack
Stacks & Queues
LC
71
Binary Search Tree Iterator
Binary Trees
LC
72
Binary Tree Cameras
Binary Trees
LC
73
Binary Tree Level Order Traversal
Binary Trees
LC
74
Binary Tree Maximum Path Sum
Binary Trees
LC
75
Count Of Smaller Numbers After Self
Binary Trees
LC
76
Diameter Of Binary Tree
Binary Trees
LC
77
Flatten Binary Tree To Linked List
Binary Trees
LC
78
Invert Binary Tree
Binary Trees
LC
79
Lowest Common Ancestor Of A Binary Tree
Binary Trees
LC
80
Maximum Depth Of Binary Tree
Binary Trees
LC
81
Same Tree
Binary Trees
LC
82
Subtree Of Another Tree
Binary Trees
LC
83
Sum Of Distances In Tree
Binary Trees
LC
84
Kth Smallest Element In A Bst
Binary Search Trees
LC
85
Lowest Common Ancestor Of A Binary Search Tree
Binary Search Trees
LC
86
Validate Binary Search Tree
Binary Search Trees
LC
87
Sliding Window Maximum
Heaps & Hashing
LC
88
Top K Frequent Elements
Heaps & Hashing
LC
89
Permutation Sequence
BONUS
LC
90
Climbing Stairs
DP
LC
91
Decode Ways
DP
LC
92
House Robber
DP
LC
93
Maximal Rectangle
DP
LC
94
Unique Paths
DP
LC
95
Accounts Merge
Graphs
LC
96
As Far From Land As Possible
Graphs
LC
97
Clone Graph
Graphs
LC
98
Evaluate Division
Graphs
LC
99
Find Eventual Safe States
Graphs
LC
100
Find The City With The Smallest Number Of Neighbors At A Threshold Distance
Graphs
LC
101
Most Stones Removed With Same Row Or Column
Graphs
LC
102
Network Delay Time
Graphs
LC
103
Satisfiability Of Equality Equations
Graphs
LC
104
Shortest Bridge
Graphs
LC
105
Snakes And Ladders
Graphs
LC
106
Distinct Subsequences
Bit Manipulation
LC
107
Candy
BONUS
LC
108
Course Schedule Ii
Graphs
LC
109
Letter Combinations Of A Phone Number
Graphs
LC
110
Making A Large Island
Graphs
LC
111
Max Consecutive Ones Iii
BONUS
LC
112
Non Overlapping Intervals
BONUS
LC
113
Number Of Provinces
Graphs
LC
114
Remove K Digits
BONUS
LC
115
Sort an Array of 0s, 1s, and 2s (Sort Colors)
BONUS
LC
116
Subarrays With K Different Integers
BONUS
LC
117
Task Scheduler
BONUS
LC
118
Word Ladder Ii
Graphs
LC
119
Add Binary
BONUS
LC
120
Angle Between Hands Of A Clock
BONUS
LC
121
Basic Calculator
BONUS
LC
122
Encode And Decode Tinyurl
BONUS
LC
123
Excel Sheet Column Title
BONUS
LC
124
Happy Number
BONUS
LC
125
Integer Break
BONUS
LC
126
Max Points On A Line
BONUS
LC
127
Maximum Product Of Three Numbers
BONUS
LC
128
Minimum Moves To Equal Array Elements
BONUS
LC
129
Missing Number
BONUS
LC
130
Number Of Digit One
BONUS
LC
131
Palindrome Number
BONUS
LC
132
Power Of Two
BONUS
LC
133
String To Integer Atoi
BONUS
LC
134
The Kth Factor Of N
BONUS
LC
135
Valid Square
BONUS
LC
136
Count Negative Numbers In A Sorted Matrix
Searching & Sorting
LC
137
Divide Two Integers
Searching & Sorting
LC
138
Find First And Last Position Of Element In Sorted Array
Searching & Sorting
LC
139
Max Sum Of Rectangle No Larger Than K
Searching & Sorting
LC
140
Minimum Limit Of Balls In A Bag
Searching & Sorting
LC
141
Peak Index In A Mountain Array
Searching & Sorting
LC
142
Search A 2D Matrix
Searching & Sorting
LC
143
Shortest Subarray With Sum At Least K
Searching & Sorting
LC
144
Sqrtx
Searching & Sorting
LC
145
Time Based Key Value Store
Searching & Sorting
LC
146
3Sum Closest
Arrays
LC
147
4Sum
Arrays
LC
148
Best Time To Buy And Sell Stock Iii
Arrays
LC
149
Find All Duplicates In An Array
Arrays
LC
150
Find Pivot Index
Arrays
LC
151
Game Of Life
Arrays
LC
152
Insert Delete Getrandom O1 Duplicates Allowed
Arrays
LC
153
Invalid Transactions
Arrays
LC
154
Jump Game Ii
Arrays
LC
155
K Diff Pairs In An Array
Arrays
LC
156
Largest Rectangle In Histogram
Arrays
LC
157
Max Area Of Island
Arrays
LC
158
Max Value Of Equation
Arrays
LC
159
Maximum Area Of A Piece Of Cake After Horizontal And Vertical Cuts
Arrays
LC
160
Maximum Points You Can Obtain From Cards
Arrays
LC
161
Move Zeroes
Arrays
LC
162
Pairs Of Songs With Total Durations Divisible By 60
Arrays
LC
163
Plus One
Arrays
LC
164
Running Sum Of 1D Array
Arrays
LC
165
Subarray Sums Divisible By K
Arrays
LC
166
Subsets
Arrays
LC
167
Add Strings
Strings
LC
168
Basic Calculator Ii
Strings
LC
169
Generate Parentheses
Strings
LC
170
Implement Strstr
Strings
LC
171
Integer To English Words
Strings
LC
172
Integer To Roman
Strings
LC
173
Minimum Remove To Make Valid Parentheses
Strings
LC
174
Reverse Words In A String
Strings
LC
175
Roman To Integer
Strings
LC
176
Simplify Path
Strings
LC
177
Smallest Range Covering Elements From K Lists
Strings
LC
178
Substring With Concatenation Of All Words
Strings
LC
179
Text Justification
Strings
LC
180
Valid Number
Strings
LC
181
Valid Palindrome Ii
Strings
LC
182
Zigzag Conversion
Strings
LC
183
Implement Queue Using Stacks
Stacks & Queues
LC
184
Next Greater Element I
Stacks & Queues
LC
185
All Nodes Distance K In Binary Tree
Binary Trees
LC
186
Balanced Binary Tree
Binary Trees
LC
187
Binary Tree Inorder Traversal/ (Using Stack Too)
Binary Trees
LC
188
Binary Tree Paths
Binary Trees
LC
189
Binary Tree Right Side View
Binary Trees
LC
190
Binary Tree Zigzag Level Order Traversal
Binary Trees
LC
191
Construct Binary Tree From Preorder And Postorder Traversal
Binary Trees
LC
192
Convert Sorted Array To Binary Search Tree
Binary Trees
LC
193
Count Good Nodes In Binary Tree
Binary Trees
LC
194
Evaluate Reverse Polish Notation
Binary Trees
LC
195
Flatten Nested List Iterator
Binary Trees
LC
196
Https://Leetcode.Com/Articles/A Recursive Approach To Segment Trees Range Sum Queries Lazy Propagation/
Segment Trees
LC
197
Maximum Width Of Binary Tree
Binary Trees
LC
198
Merge Two Binary Trees
Binary Trees
LC
199
Minimum Absolute Difference In Bst
Binary Trees
LC
200
Minimum Cost Tree From Leaf Values
Binary Trees
LC
201
Number Of Ways To Reconstruct A Tree
Binary Trees
LC
202
Online Stock Span
Binary Trees
LC
203
Path Sum
Binary Trees
LC
204
Path Sum Iii
Binary Trees
LC
205
Populating Next Right Pointers In Each Node
Binary Trees
LC
206
Range Sum Of Bst
Binary Trees
LC
207
Redundant Connection Ii
Binary Trees
LC
208
Remove All Adjacent Duplicates In String Ii
Binary Trees
LC
209
Sum Of Left Leaves
Binary Trees
LC
210
Sum Of Subarray Minimums
Binary Trees
LC
211
Symmetric Tree
Binary Trees
LC
212
Unique Binary Search Trees
Binary Trees
LC
213
Unique Binary Search Trees Ii
Binary Trees
LC
214
Vertical Order Traversal Of A Binary Tree
Binary Trees
LC
215
Find The Most Competitive Subsequence
Heaps & Hashing
LC
216
Furthest Building You Can Reach
Heaps & Hashing
LC
217
K Closest Points To Origin
Heaps & Hashing
LC
218
K Th Smallest Prime Fraction
Heaps & Hashing
LC
219
Kth Smallest Element In A Sorted Matrix
Heaps & Hashing
LC
220
Minimum Cost To Hire K Workers
Heaps & Hashing
LC
221
Minimum Number Of Refueling Stops
Heaps & Hashing
LC
222
Reorganize String
Heaps & Hashing
LC
223
Shortest Path To Get All Keys
Heaps & Hashing
LC
224
Trapping Rain Water Ii
Heaps & Hashing
LC
225
Ugly Number Ii
Heaps & Hashing
LC
226
Https://Leetcode.Com/Explore/Learn/Card/Trie/
Tries
LC
227
Best Time To Buy And Sell Stock Iv
DP
LC
228
Continuous Subarray Sum
DP
LC
229
Count Different Palindromic Subsequences
DP
LC
230
Count Square Submatrices With All Ones
DP
LC
231
Counting Bits
DP
LC
232
Delete And Earn
DP
LC
233
Divisor Game
DP
LC
234
Knight Dialer
DP
LC
235
Longest Arithmetic Subsequence
DP
LC
236
Longest Valid Parentheses
DP
LC
237
Maximal Square
DP
LC
238
Maximum Length Of Repeated Subarray
DP
LC
239
Minimum Cost To Cut A Stick
DP
LC
240
Minimum Cost To Merge Stones
DP
LC
241
Minimum Difficulty Of A Job Schedule
DP
LC
242
Minimum Insertion Steps To Make A String Palindrome
DP
LC
243
Range Sum Query 2D Immutable
DP
LC
244
Super Egg Drop
DP
LC
245
Word Break Ii
DP
LC
246
Employee Importance
Graphs
LC
247
Find The Town Judge
Graphs
LC
248
Keys And Rooms
Graphs
LC
249
Number Of Closed Islands
Graphs
LC
250
Possible Bipartition
Graphs
LC
251
Time Needed To Inform All Employees
Graphs
LC
252
Sum Of Two Integers/Discuss/84278/A Summary%3A How To Use Bit Manipulation To Solve Problems Easily And Efficiently
Bit Manipulation
LC
253
24 Game
Graphs
LC
254
All Oone Data Structure
BONUS
LC
255
All Paths From Source To Target
Graphs
LC
256
Concatenated Words
Graphs
LC
257
Contain Virus
Graphs
LC
258
Create Maximum Number
BONUS
LC
259
Critical Connections In A Network
Graphs
LC
260
Cut Off Trees For Golf Event
Graphs
LC
261
Decode String
Graphs
LC
262
Design Browser History
BONUS
LC
263
Design Hashmap
Heaps & Hashing
LC
264
Design Twitter
Heaps & Hashing
LC
265
Design Underground System
BONUS
LC
266
Grumpy Bookstore Owner
BONUS
LC
267
House Robber Iii
Graphs
LC
268
Is Graph Bipartite
Graphs
LC
269
Lfu Cache
BONUS
LC
270
Longest Increasing Path In A Matrix
Graphs
LC
271
Longest Substring With At Least K Repeating Characters
BONUS
LC
272
Maximum Number Of Events That Can Be Attended
BONUS
LC
273
Maximum Number Of Visible Points
BONUS
LC
274
Minimum Deletion Cost To Avoid Repeating Letters
BONUS
LC
275
Minimum Deletions To Make Character Frequencies Unique
BONUS
LC
276
Minimum Jumps To Reach Home
Graphs
LC
277
Minimum Number Of Taps To Open To Water A Garden
BONUS
LC
278
Reachable Nodes In Subdivided Graph
Graphs
LC
279
Remove Boxes
Graphs
LC
280
Restore The Array From Adjacent Pairs
BONUS
LC
281
Sliding Window Median
BONUS
LC
282
Surrounded Regions
Graphs
LC
283
Tweet Counts Per Frequency
BONUS
LC
284
Verifying An Alien Dictionary
Heaps & Hashing
LC