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DSA Questions

225 questions · sorted by topic progression · click any question to open on LeetCode

225 / 2250
Difficulty
Topic
Company
Two Sum
arrays
10 co.easy
Best Time to Buy and Sell Stock
arrays
7 co.easy
Contains Duplicate
arrays
6 co.easy
Maximum Subarray
arraysdp
11 co.easy
Move Zeroes
arraystwo pointers
5 co.easy
Single Number
arrays
3 co.easy
Intersection of Two Arrays II
arrays
3 co.easy
Plus One
arrays
2 co.easy
Merge Sorted Array
arraystwo pointers
6 co.easy
Pascal's Triangle
arraysdp
3 co.easy
Valid Anagram
strings
7 co.easy
Valid Palindrome
stringstwo pointers
6 co.easy
Reverse String
stringstwo pointers
3 co.easy
First Unique Character in a String
strings
4 co.easy
Implement strStr()
stringstwo pointers
4 co.easy
Longest Common Prefix
strings
4 co.easy
Roman to Integer
stringsmath
4 co.easy
Count and Say
strings
3 co.easy
3Sum
arraystwo pointers
7 co.medium
Product of Array Except Self
arrays
5 co.medium
Find Minimum in Rotated Sorted Array
arraysbinary search
5 co.medium
Search in Rotated Sorted Array
arraysbinary search
6 co.medium
Container With Most Water
arraystwo pointers
5 co.medium
Rotate Array
arrays
3 co.medium
Subarray Sum Equals K
arrays
4 co.medium
Sort Colors
arraystwo pointers
5 co.medium
Next Permutation
arraystwo pointers
3 co.medium
Jump Game
arraysgreedy
6 co.medium
Spiral Matrix
arrays
5 co.medium
Set Matrix Zeroes
arrays
4 co.medium
Two Sum II
arraystwo pointers
3 co.medium
4Sum
arraystwo pointers
2 co.medium
Remove Duplicates from Sorted Array
arraystwo pointers
5 co.easy
Trapping Rain Water
arraystwo pointers
8 co.hard
Squares of a Sorted Array
arraystwo pointers
3 co.easy
Longest Substring Without Repeating Characters
stringssliding window
9 co.medium
Minimum Window Substring
stringssliding window
6 co.hard
Permutation in String
stringssliding window
4 co.medium
Longest Repeating Character Replacement
stringssliding window
4 co.medium
Maximum Sum Subarray of Size K
arrayssliding window
3 co.medium
Binary Search
arraysbinary search
6 co.easy
Search a 2D Matrix
arraysbinary search
6 co.medium
Koko Eating Bananas
arraysbinary search
2 co.medium
Median of Two Sorted Arrays
arraysbinary search
5 co.hard
Find Peak Element
arraysbinary search
5 co.medium
Time Based Key-Value Store
arraysbinary search
3 co.medium
Valid Parentheses
stacks
9 co.easy
Min Stack
stacks
6 co.medium
Evaluate Reverse Polish Notation
stacks
3 co.medium
Daily Temperatures
stacks
5 co.medium
Car Fleet
stacks
2 co.medium
Largest Rectangle in Histogram
stacks
6 co.hard
Next Greater Element I
stacks
2 co.easy
Implement Queue using Stacks
stacksqueues
4 co.easy
Reverse Linked List
linked lists
10 co.easy
Merge Two Sorted Lists
linked lists
7 co.easy
Linked List Cycle
linked liststwo pointers
8 co.easy
Remove Nth Node From End of List
linked liststwo pointers
4 co.medium
Reorder List
linked liststwo pointers
4 co.medium
LRU Cache
linked lists
8 co.medium
Merge K Sorted Lists
linked listsheaps
6 co.hard
Copy List with Random Pointer
linked lists
5 co.medium
Find the Duplicate Number
linked liststwo pointers
3 co.medium
Reverse Nodes in k-Group
linked lists
4 co.hard
Invert Binary Tree
trees
6 co.easy
Maximum Depth of Binary Tree
trees
6 co.easy
Symmetric Tree
trees
4 co.easy
Path Sum
trees
3 co.easy
Binary Tree Level Order Traversal
trees
9 co.medium
Validate Binary Search Tree
trees
7 co.medium
Lowest Common Ancestor of BST
trees
7 co.medium
Binary Tree Right Side View
trees
5 co.medium
Count Good Nodes in Binary Tree
trees
3 co.medium
Kth Smallest Element in BST
trees
4 co.medium
Construct Binary Tree from Preorder and Inorder
trees
5 co.medium
Binary Tree Maximum Path Sum
trees
6 co.hard
Serialize and Deserialize Binary Tree
trees
5 co.hard
Diameter of Binary Tree
trees
6 co.easy
Balanced Binary Tree
trees
5 co.easy
Kth Largest Element in an Array
heapsarrays
8 co.medium
Top K Frequent Elements
heapsarrays
8 co.medium
Find Median from Data Stream
heaps
6 co.hard
Task Scheduler
heapsgreedy
5 co.medium
K Closest Points to Origin
heapsarrays
4 co.medium
Number of Islands
graphs
12 co.medium
Clone Graph
graphs
6 co.medium
Max Area of Island
graphs
4 co.medium
Pacific Atlantic Water Flow
graphs
5 co.medium
Surrounded Regions
graphs
3 co.medium
Rotting Oranges
graphs
6 co.medium
Course Schedule
graphs
8 co.medium
Course Schedule II
graphs
5 co.medium
Graph Valid Tree
graphs
4 co.medium
Number of Connected Components
graphs
3 co.medium
Redundant Connection
graphs
3 co.medium
Word Ladder
graphs
5 co.hard
Walls and Gates
graphs
5 co.medium
Alien Dictionary
graphs
5 co.hard
Swim in Rising Water
graphs
2 co.hard
Network Delay Time
graphs
5 co.medium
Subsets
backtracking
5 co.medium
Combination Sum
backtracking
6 co.medium
Permutations
backtracking
5 co.medium
Word Search
backtracking
6 co.medium
Palindrome Partitioning
backtracking
4 co.medium
Letter Combinations of a Phone Number
backtracking
5 co.medium
N-Queens
backtracking
4 co.hard
Subsets II
backtracking
3 co.medium
Jump Game II
greedyarrays
6 co.medium
Gas Station
greedy
4 co.medium
Hand of Straights
greedy
2 co.medium
Partition Labels
greedy
3 co.medium
Valid Parenthesis String
greedystacks
4 co.medium
Merge Intervals
greedyarrays
11 co.medium
Insert Interval
greedyarrays
6 co.medium
Non-overlapping Intervals
greedyarrays
4 co.medium
Climbing Stairs
dp
8 co.easy
Min Cost Climbing Stairs
dp
3 co.easy
House Robber
dp
5 co.medium
House Robber II
dp
4 co.medium
Longest Palindromic Substring
dpstrings
5 co.medium
Palindromic Substrings
dpstrings
3 co.medium
Decode Ways
dpstrings
6 co.medium
Coin Change
dp
9 co.medium
Maximum Product Subarray
dparrays
5 co.medium
Word Break
dpstrings
9 co.medium
Longest Increasing Subsequence
dp
8 co.medium
Partition Equal Subset Sum
dp
4 co.medium
Unique Paths
dp
5 co.medium
Longest Common Subsequence
dpstrings
6 co.medium
Best Time to Buy and Sell Stock with Cooldown
dparrays
3 co.medium
Coin Change II
dp
4 co.medium
Target Sum
dpbacktracking
4 co.medium
Interleaving String
dpstrings
4 co.medium
Longest Increasing Path in a Matrix
dpgraphs
4 co.hard
Distinct Subsequences
dpstrings
3 co.hard
Edit Distance
dpstrings
6 co.medium
Burst Balloons
dp
5 co.hard
Regular Expression Matching
dpstrings
5 co.hard
Cheapest Flights Within K Stops
graphs
6 co.medium
Path with Maximum Probability
graphs
3 co.medium
Reconstruct Itinerary
graphs
4 co.hard
Min Cost to Connect All Points
graphs
4 co.medium
Find Critical and Pseudo-Critical Edges
graphs
3 co.hard
Reverse Bits
math
4 co.easy
Number of 1 Bits
math
4 co.easy
Counting Bits
dpmath
3 co.easy
Missing Number
matharrays
4 co.easy
Sum of Two Integers
math
4 co.medium
Pow(x, n)
math
4 co.medium
Group Anagrams
strings
8 co.medium
Longest Palindrome
strings
3 co.easy
Encode and Decode Strings
strings
5 co.medium
Find All Anagrams in a String
stringssliding window
4 co.medium
Minimum Number of Arrows to Burst Balloons
greedyarrays
3 co.medium
Basic Calculator II
stacksstrings
4 co.medium
Implement Trie
trees
5 co.medium
Design Add and Search Words Data Structure
trees
4 co.medium
Word Search II
treesbacktracking
4 co.hard
Meeting Rooms
arraysgreedy
5 co.easy
Meeting Rooms II
heapsgreedy
6 co.medium
Flood Fill
graphs
4 co.easy
Maximum Meetings in One Room
greedy
3 co.medium
Minimum Platforms
greedyarrays
5 co.medium
Stock Buy and Sell Multiple
greedyarrays
4 co.medium
Rat in a Maze
backtrackinggraphs
3 co.medium
Reverse Words in a String
strings
4 co.medium
Rotate Image
arrays
6 co.medium
Decode String
stacksstrings
4 co.medium
Random Pick with Weight
mathbinary search
4 co.medium
Design HashMap
arrays
4 co.easy
Insert Delete GetRandom O(1)
arrays
5 co.medium
LFU Cache
linked lists
5 co.hard
Alien Dictionary Verify Order
strings
3 co.easy
Sliding Window Maximum
sliding windowqueues
6 co.hard
Word Break II
dpbacktracking
5 co.hard
Number of Ways to Reorder Array to Get Same BST
treesdp
2 co.hard
Maximum Width of Binary Tree
trees
4 co.medium
Flatten Binary Tree to Linked List
treeslinked lists
5 co.medium
Populating Next Right Pointers in Each Node
trees
4 co.medium
Check Completeness of a Binary Tree
trees
3 co.medium
All Nodes Distance K in Binary Tree
treesgraphs
4 co.medium
Amount of Time for Binary Tree to Be Infected
treesgraphs
3 co.medium
Count Complete Tree Nodes
treesbinary search
3 co.easy
Find Duplicate Subtrees
trees
3 co.medium
Number of Provinces
graphs
5 co.medium
Shortest Path in Binary Matrix
graphs
4 co.medium
As Far from Land as Possible
graphs
3 co.medium
Evaluate Division
graphs
5 co.medium
Minimum Height Trees
graphstrees
4 co.medium
Keys and Rooms
graphs
3 co.medium
Find the Town Judge
graphs
3 co.easy
Course Schedule IV
graphs
3 co.medium
Maximum Number of Vowels in a Substring
sliding windowstrings
3 co.medium
Minimum Size Subarray Sum
sliding windowarrays
5 co.medium
Frequency of the Most Frequent Element
sliding windowarrays
3 co.medium
Fruit Into Baskets
sliding windowarrays
3 co.medium
Longest Subarray of 1s After Deleting One Element
sliding windowarrays
3 co.medium
Maximum Consecutive Ones III
sliding windowarrays
4 co.medium
Minimum Consecutive Cards to Pick Up
sliding windowarrays
2 co.medium
Convert Binary Number in Linked List to Integer
linked listsmath
1 co.easy
Asteroid Collision
stacksarrays
3 co.medium
Find First and Last Position of Element in Sorted Array
arraysbinary search
4 co.medium
Game of Life
arrays
3 co.medium
First Missing Positive
arrays
4 co.hard
Find All Numbers Disappeared in an Array
arrays
4 co.easy
Set Mismatch
arraysmath
3 co.easy
Find All Duplicates in an Array
arrays
4 co.medium
132 Pattern
stacksarrays
3 co.medium
Isomorphic Strings
strings
4 co.easy
Happy Number
mathtwo pointers
4 co.easy
Linked List Cycle II
linked liststwo pointers
4 co.medium
Add Two Numbers
linked listsmath
6 co.medium
Swap Nodes in Pairs
linked lists
4 co.medium
Rotate List
linked liststwo pointers
4 co.medium
Range Sum Query - Immutable
arraysdp
4 co.easy
Continuous Subarray Sum
arraysmath
4 co.medium
Accounts Merge
graphsstrings
5 co.medium
Minimum Number of Platforms
arraysgreedy
6 co.medium
Median of Two Sorted Arrays
arraysbinary search
5 co.hard
Count Subsequences That Satisfy the Given Sum Condition
arraystwo pointers
3 co.medium
Design Hit Counter
queuesbinary search
5 co.medium
Maximum Product of Word Lengths
arraysmath
3 co.medium
Number of Submatrices That Sum to Target
arraysdp
4 co.hard
Minimum Platforms Required
arraysgreedy
4 co.medium