Completed Problems

██▓▒░⡷⠂Leetcode⠐⢾░▒▓██

Sort Colors
Maximum Subarray
Last Stone Weight
Find The Duplicate Number --IMP --Revise
Determine if Two Strings Are Close
Design an Ordered Stream
Minimum Operations to Reduce X to Zero
House Robber (DP)
Coin Change 2 (DP)
Coin Change (DP)
Edit Distance(DP) --IMP --Hard
Longest_Common_Subsequence (DP)
Jump Game II (DP) --Revise --IMP
First Unique Character in a String
Best Time to Buy and Sell Stock (DP)
Best Time to Buy and Sell Stock 2 (DP)
Best Time to Buy and Sell Stock 3 (DP) --Hard --Revise
Best Time to Buy and Sell Stock 4 (DP) --Hard --Revise
Jump Game (Greedy)
Richest Customer Wealth
Find the Most Competitive Subsequence (Stack) --IMP
Maximum Depth of Binary Tree (Tree)
Shortest Word Distance (Two-pointer)
Linked List Random Node (Randomized Algo) --IMP
Two Sum
Binary Tree Inorder Traversal (Tree)
Increasing_Order_Search_Tree (Tree)
The kth Factor of n
Can Place Flowers
Goal Parser Interpretation
Max Number of K-Sum Pairs
Populating Next Right Pointers in Each Node II
Spiral Matrix II
Pairs of Songs With Total Durations Divisible by 60
Binary Search Tree Iterator (Tree)
Valid Mountain Array
Remove Duplicates from Sorted Array II
Count the Number of Consistent Strings
Sum of Absolute Differences in a Sorted Array
Smallest Subtree with all the Deepest Nodes
Burst Baloons (LR DP) --IMP Concept --Hard
Palindrome Partitioning (Backtracking) --IMP
Squares of a Sorted Array
Plus One Linked List
Validate Binary Search Tree (BST) --IMP
4Sum II
Increasing Triplet Subsequence --IMP
Cherry Pickup II
Decoded String at Index --Hard
Smallest Range II --Tricky --Revise
Swap Nodes in Pairs --Revise
Diagonal Traverse
Number of Students Unable to Eat Lunch
Average Waiting Time
Determine if String Halves Are Alike
Middle of the Linked List
Rotate List
Reverse Linked List
Jump Game IV (BFS) --IMP
Reach a Number --Tricky --IMP
Partition Equal Subset Sum (DP)
Target Sum (DP) --IMP
Combination Sum (DP) (Backtracing) --IMP --Revise
Combination Sum II (Backtracking) --IMP --Revise
Maximum Number of Balls in a Box
Number of 1 Bits
Trim a Binary Search Tree (Tree)
Linked List Cycle
Search in a Binary Search Tree (Tree)
Arithmetic Slices (DP) --IMP --Revise
Number of Islands (DFS on grid) (Graphs)
Distribute Candies
Set Mismatch
Missing Number
Intersection of Two Linked Lists
Average of Levels in Binary Tree
Short Encoding of Words --Revise
Design HashMap
Remove Palindromic Subsequences
Add One Row to Tree (Tree) --Revise
Integer to Roman
Check If a String Contains All Binary Codes of Size K --Revise
Binary Trees With Factors (DP) --Revise ---IMP
Swapping Nodes in a Linked List
Best Time to Buy and Sell Stock with Transaction Fee (DP) --Revise ---IMP
Invert Binary Tree (Tree)
Add Two Numbers
Wiggle Subsequence (DP) --Revise --IMP
Max Consecutive Ones III (Slding Window) --IMP
Keys and Rooms (DFS)
Longest Substring Without Repeating Characters (Sliding Window)
Course Schedule (Graphs) --IMP
Second Largest Digit in a String
Design Authentication Manager
Reordered Power of 2
Find a Corresponding Node of a Binary Tree in a Clone of That Tree (Tree)
Sum of Nodes with Even-Valued Grandparent (Tree)
Deepest Leaves Sum (Tree)
Range Sum of BST (Tree)
Binary Search (Binary Search)
Valid Square
Check if the Sentence Is Pangram
Maximum Ice Cream Bars (Sorting)
Replace All Digits with Characters
Seat Reservation Manager
Maximum Element After Decreasing and Rearranging (Sorting)
Range Sum of Sorted Subarray Sums (Prefix Sum)
Range Sum Query 2D - Immutable (DP)
Minimum Distance to the Target Element
Splitting a String Into Descending Consecutive Values (Backtracking)
Next Permutation --Revise --IMP
Non-decreasing Array --Revise --Tricky
Path Sum (Tree)
Search in Rotated Sorted Array (Binary Search)
Climbing Stairs (DP)
Convert Sorted List to Binary Search Tree (DnC) (Tree) --Revise --Tricky
Find First and Last Position of Element in Sorted Array (Binary Search) --IMP
First Bad Version (Binary Search)
Rotting Oranges (BFS)
Delete Operation for Two Strings (DP)
Capacity To Ship Packages Within D Days (Binary Search) --Revise --IMP
Koko Eating Bananas (Binary Search) --Revise
Maximum Population Year
Maximum Distance Between a Pair of Values (Binary Search)
Split Array Largest Sum (Binary Search) --Revise --Hard
Maximum Points You Can Obtain from Cards (Sliding Window) (Prefix Sum)
Minimum Number of Days to Make m Bouquets (Binary Search) --Revise
Sorting the Sentence
Incremental Memory Leak
Rotating the Box
Daily Temperatures( Monotonic Stack)
Product of Array Except Self --IMP
Maximum Erasure Value (Slidign Window)
Out of Boundary Paths (DP)
3Sum (Two Pointer)
Find K Closest Elements (Binary Search) --IMP --Tricky --Revise
Maximum Product Difference Between Two Pairs (Sorting)
Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold (Sliding Window)
Same Tree (Tree)
Symmetric Tree (Tree)
Kth Smallest Element in a BST (Tree)
Eliminate Maximum Number of Monsters (Greedy) (Priority Queue) --IMP
All Paths From Source to Target (Graphs) (DFS) --IMP
Video Stitching (DP) (Greedy) --Revise
Max Area of Island (DFS)
Island Perimeter (DFS)
Path Sum II (Tree) (DFS)
Reduce Array Size to The Half
Merge k Sorted Lists (Linked List) --HARD --Revise
Merge Intervals (Greedy)
Two City Scheduling (Greedy)
Minimum Number of Arrows to Burst Balloons (Greedy) (Line Sweep)
Find Bottom Left Tree Value (Tree)
Combination Sum III (Backtracking)
Smallest Range I
Valid Triangle Number (Two Pointer)
Non-Overlapping Intervals (Greedy)
Remove Nth Node From End of List
Maximum Profit in Job Scheduling (DP + Binary Search) --Hard --IMP
Surrounded Regions (DFS)
Nearest Exit from Entrance in Maze (BFS)
Course Schedule II (Graphs) (Topsort)
Nim Game
Delete and Earn (DP) --IMP --Revise --Tricky
Contains Duplicate
Maximum Difference Between Node and Ancestor (Tree) --IMP
Unique Paths (DP)
Binary Tree Pruning (Tree)
Minimum ASCII Delete Sum for Two Strings (DP)
3Sum Closest (Two Pointer)
Matrix Block Sum (Prefix Sum)
Decrease Elements To Make Array Zigzag --Revise
Reverse Words in a String III
Find Minimum Time to Finish All Jobs (Binary Search) (DFS) --Revise --IMP --Hard
Minimum Limit of Balls in a Bag (Binary Search) --Tricky --Revise
Longest Happy Prefix (KMP)
Shortest Palindrome (KMP)
Stone Game (Greedy)
Minimum Path Sum (Grid DP)
Jump Game III (BFS)
Plus One
Critical Connections in a Network (Graphs) (Bridges) --Hard --Revise
Minimum Height Trees (Graphs) (Center of Tree) --IMP
Kth Ancestor of a Tree Node (Graphs) (Binary Lifting) --IMP --Hard
Design Add and Search Words Data Structure (Trie)
Last Day Where You Can Still Cross (Binary Search) (BFS)
Array With Elements Not Equal to Average of Neighbors
Group the People Given the Group Size They Belong To
Number of Substrings With Only 1s
Binary Tree Maximum Path Sum --Revise --IMP
Count Vowels Permutation (DP)
Sum of Even Numbers After Queries
Palindromic Substrings (DP)
Longest Palindromic Substring (DP) --Revise --IMP
Minimum Number of Vertices to Reach All Nodes (Graph) --Revise
Redundant Connection (DSU)
Binary Tree Zigzag Level Order Traversal (Tree) (BFS)
Minimum Size Subarray Sum (Sliding Window)
Longest Palindromic Subsequence (DP) --Revise
Contiguous Array --IMP CONCEPT __Revise
Number of Ways to Arrive at Destination (Graphs) (Dijkstra) --IMP
Array Nesting (DSU)
Path with Maximum Probability (Graphs) (Dijkstra)
Top K Frequent Elements (Bucket Sort) --IMP concept
Unique Paths II (DP)
Number of Operations to Make Network Connected (DSU)
Find Minimum in Rotated Sorted Array (Binary Search)
Global and Local Inversions (Merge Sort) --IMP Concept
Find Eventual Safe States (Graphs) (DFS)
Longest Increasing Subsequence (DP)
Letter Combinations of a Phone Number (Backtracking)
Maximal Square (DP)
Word Break (DP)
Palindrome Partitioning II (DP) (DnC DP)
Stone Game II (DP) (Game Theory)
Stone Game VII (DP) (Game Theory)
House Robber II (DP)
Maximum Length of Pair Chain (DP)
Convert BST to Greater Tree (BST)
Complete Binary Tree Inserter (Tree)
Construct K Palindrome Strings
Cherry Pickup (DP) (Grid DP) --IMP concept
Decode Ways (DP)
Insertion Sort List (Linked List) --IMP
Binary Tree Level Order Traversal II
Word Ladder (BFS)
Numbers At Most N Given Digit Set (Digit DP) --IMP Concept --HARD
Word Ladder II (BFS) --Hard
Decode String
Stone Game III (DP) (Game Theory) --HARD --IMP
Decode XORed Array
Maximum XOR With an Element From Array (Sorting + BIT Trie) --HARD --IMP
Maximum XOR of Two Numbers in an Array (BIT Trie) --Revise
Merge In Between Linked Lists (Linked List)
Maximum Score from Performing Multiplication Operations (DP)
Binary Subarrays With Sum (Sliding Window + HashMap) --IMP --Tricky --Revise
Subarray Sum Equals K (Sliding Window + HashMap) --IMP --Tricky --Revise
Graph Connectivity With Threshold (DSU + Seive) --Hard
Balance a Binary Search Tree (BST)
Furthest Building You Can Reach (Greedy) (Priority Queue) --IMP
Network Delay Time (Graphs) (Dijkstra)
Longest Substring with At Least K Repeating Characters (Sliding Window) --New CONCEPT --IMP
Longest Increasing Path in a Matrix (DP + DFS on matrix) --Concept --IMP --HARD
Max Increase to Keep City Skyline
Car Pooling (Partial and Prefix Sums) --Revise
Maximum Fruits Harvested After at Most K Steps (Prefix Sums) --HARD --IMP --Revise
Count Servers that Communicate
Maximum Score Words Formed by Letters
Number of Laser Beams in a Bank
Destroying Asteroids (Sorting)
Execution of All Suffix Instructions Staying in a Grid
Intervals Between Identical Elements (Prefix Sum) --IMP --Revise
Evaluate Reverse Polish Notation (Stack)
Maximum Twin Sum of a Linked List
Longest Palindrome by Concatenating Two Letter Words
Robot Bounded In Circle --Tricky --Revise
Minimum Swaps to Group All 1's Together II (Sliding Window) --IMP --Revise
Count Words Obtained After Adding a Letter (Trie) --Revise
Increasing Subsequences (Backtrack) --Tricky --Revise --IMP
Sliding Window Maximum (Monotonic Queue) --IMP
Max Value of Equation (Monotonic Queue) --Tricky for Monoque
Maximal Network Rank (Graphs)
Trapping Rain Water (Greedy) --IMP
Count Good Meals --Tricky
Maximum Number of Coins You Can Get (Sorting) (Greedy)
Palindrome Partitioning III (DP) --IMP --Revise
Palindrome Partitioning IV (DP) --IMP --Revise
Earliest Possible Day of Full Bloom (Greedy)
Stone Game IV (DP) (Game Theory)
Stone Game V (DnC DP)
Stone Game VI (Greedy) --IMP --Revise
Maximum Level Sum of a Binary Tree (BFS)
Stone Game VIII (Game Theory DP) --Tricky Optimization --Revise
Sum of Subarray Ranges (MonoStack) --Tricky --V IMP
Sum of Subarray Minimums (MonoStack)
Maximize Distance to Closest Person (Two Pointer)
Dungeon Game (Grid DP) --Very IMP --Tricky
Solving Questions With Brainpower (Knapsack DP)
Container With Most Water (Two Pointer) (Greedy) --IMP
Delete Node in a BST --Tricy --IMP --Revise
Linked List Cycle II
Minimum Swaps To Make Sequences Increasing (DP) --IMP
Closest Divisors
Constrained Subsequence Sum (DP + MonoQueue) --New Concept --TOUGH --IMP --Revise
Remove Sub-Folders from the Filesystem (Trie)
Count Primes (Seive of Eratothenes)
Number of Pairs of Interchangeable Rectangles
Maximum Height by Stacking Cuboids (DP) --TOUGH --IMP --Revise
Gas Station (Two Pointer) --Tricky
Closest Dessert Cost (Backtracking) --Concept Revise
Shortest Subarray with Sum at Least K (Monoqueue+Prefix Sum) --V.V.IMP --Must Revise
Count Good Nodes in Binary Tree (DFS)
Count the Hidden Sequences (Math) --Read editorial
Path with Maximum Gold (Backtracking)
Sequential Digits
Partition Labels (Two Pointer)
Maximum Length of Subarray With Positive Product (DP) --IMP --Must Revise
Range Sum Query - Mutable (Segment Tree)
Perfect Rectangle (Observation Based)
Watering Plants
Longest Word in Dictionary through Deleting (Two Pointer)
The Skyline Problem (SweepLine) --Must Revise
Number of Provinces (DSU)
K Closest Points to Origin (PriorityQueue)
Integer Replacement (DP)
All Elements in Two Binary Search Trees (BST) --Concept --Revise
Print Words Vertically
Minimum Number of Taps to Open to Water a Garden (Greedy) --Concept
The k-th Lexicographical String of All Happy Strings of Length n
Minimize Maximum Pair Sum in Array (Greedy)
Rotate Array --Tricky --Revise --IMP
Shortest Common Supersequence (DP)
Partitioning Into Minimum Number Of Deci-Binary Numbers
Task Scheduler (Priority Queue) --Revise --Imp --Tricky
Number of Enclaves (DFS on grid)
Number of Closed Islands (DFS on Grid) --Revise
Check If Array Pairs Are Divisible by k --Tricky --V. IMP --CONCEPT --Revise
Find All Anagrams in a String (Fixed Sliding Window)
Count Number of Teams (Prefix and Suffix Count) --V.IMP --Concept -- Revise
Minimum Number of Increments on Subarrays to Form a Target Array --V. V. Tricky
Numbers With Same Consecutive Differences (Recursion)
Reducing Dishes (Knapsack Type DP)
Predict the Winner (Game Theory DP)
Word Search (DFS)
Relative Sort Array (Coordinate Compression)
Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts (Greedy) --IMP --Revise
Grid Game (Prefix Sum)
Map Sum Pairs (Trie)
Minimum Interval to Include Each Query (Line Sweep) --Tough --Concept
Partition Array According to Given Pivot
Remove K Digits (Monotonic Queue)
Majority Element (Majority Vote Algorithm) --IMP --Revise
Number of Orders in the Backlog (2 Heaps) --Solved in One go
K-diff Pairs in an Array (HashMap)
Letter-case Permutation
Distribute Coins in Binary Tree (DFS) --Tricky --IMP
Delete Leaves With a Given Value (PostOrder)
Candy (Greedy) --CONCEPT --Tricky --IMP --REVISE
Meeting Rooms II (Sweep Line) (Solved on InterviewBit)
Shortest Path with Alternating Colors (BFS) --CONCEPT --Tricky
Unique Binary Search Trees II (DnC algorithm) --IMP --REVISE
Minimize Hamming Distance After Swap Operations (Union Find) --Concept with implementation heavy
Permutation in String (Fixed Sliding Window)
Subsets
Largest Divisible Subset (DP) --Tricky
Maximum Number of Vowels in a Substring of Given Length (Fixed Sliding Window)
Min Cost to Connect All Points (Kruskal MST) --Revise --IMP
Smallest String With Swaps (DSU) --IMP
Minimum Operations to Make the Array Alternating
Removing Minimum Number of Magic Beans (Prefix Sum) --CONCEPT --IMP
Permutations (Backtracking)
Additive Number (Backtracking) --Crazy Tricky level
Max Chunks To Make Sorted (Greedy) --IMP
Minimum Elements to Add to Form a Given Sum
Max Chunks To Make Sorted II (Greedy) --CONCEPT --IMP
Minimize Deviation in Array (Greedy) --IMP --HARD --Revise --Tricky
Insert Delete GetRandom O(1) --Tricky
Find Three Consecutive Integers That Sum to a Given Number
Maximum Split of Positive Even Integers
Remove Covered Intervals (Greedy)
Lowest Common Ancestor of a Binary Tree(Tree) --Revise
Merge Nodes in Between Zeros
Construct String With Repeat Limit (Greedy)
Sum of Distances in Tree (Tree DP) --HARD --Tricky --IMP --REVISE --Concept
Longest ZigZag Path in a Binary Tree (Tree DP) --IMP
Minimum Remove to Make Valid Parentheses (Stack) --Tricky --Revise
Find K-th Smallest Pair Distance (Binary Search + Sliding Window) --V Tough --Concept
Count Array Pairs Divisible by K (HashMap + Math) --Concept --IMP
Minimum Deletions to Make String Balanced (DP) --IMP --Revise
Longest Repeating Character Replacement (Sliding Window)
Number of Sub-arrays With Odd Sum (Prefix Sum) --IMP --REVISE
Subarray Sums Divisible by K (Prefix Sum) --IMP --REVISE
Max Sum of Rectangle No Larger Than K (Prefix Sum + TreeSet)
Sort List (Merge Sort) --IMP
Maximum Sum Obtained of Any Permutation (Partial Sums)
Reverse Substrings Between Each Pair of Parentheses (Stack + Queue)
Reverse Nodes in k-Group --Implementation Heavy
Longest Consecutive Sequence (DSU) --IMP --Revise
Shortest Path Visiting All Nodes (Graphs + DP) --Tricky --HARD
Minimum Number of Steps to Make Two Strings Anagram II
Minimum Time to Complete Trips (Binary Search)
Numbers With Repeated Digits (Digit DP) --IMP --Revise
Maximum Width of Binary Tree (Tree) --V.V IMP
Evaluate Division (Graphs)
Vowels of All Substrings --Concept
Most Stones Removed with Same Row or Column (DSU)
Largest Component Size by Common Factor (DSU + Number Theory) --Concept --IMP --Revise
Queens That Can Attack the King
Combination Sum IV (DP) --IMP --REVISE
Maximum Alternating Subsequence Sum (DP) --IMP --REVISE
Group Anagrams
Least Number of Unique Integers after K Removals (Greedy) --Revise
Maximum Score of a Good Subarray (Two Pointers) --Tricky Implementation
Minimum Cost to Cut a Stick (DnC DP) --Tricy --Concept
Minimum Time to Collect All Apples in a Tree (DFS) --Revise
XOR Queries of a Subarray
Count of Smaller Numbers After Self (Segment Tree) --IMP --REVISE
Minimum Flips to Make a OR b Equal to c
Maximum XOR for Each Query
Find Duplicate Subtrees (Tree)
Binary String With Substrings Representing 1 To N
Is Graph Bipartite (Graphs)
Champagne Tower (DP)
Sort the Jumbled Numbers
All Ancestors of a Node in a Directed Acyclic Graph (Graphs) --IMP --Revise
Minimum Number of Moves to Make Palindrome (Two Pointers) --Hard --IMP -Revise
Count Complete Tree Nodes (Tree) --Revise --IMP
Remove Duplicates from Sorted List II (LinkedList)
Longest Univalue Path (Tree DP)
Insert Interval
Copy List with Random Pointer --Tricky
Next Greater Element II (Monotonic Stack) --IMP
Next Greater Element III (Greedy) --IMP
Minimum Insertion Steps to Make a String Palindrome (DP) -IMP
Simplify Path (Stack)
Word Break II (DP)
HTML Entity Parser
Maximum Width Ramp (TreeMap) --IMP --Revise
Remove Max Number of Edges to Keep Graph Fully Traversable (2 DSU approach) --IMP --Revise
Validate Stack Sequences (Stack)
Score of Parentheses (Stack) Tough --Revise
Find Two Non-overlapping Sub-arrays Each With Target Sum (Prefix Sum, Suffix Min) --CONCEPT --IMP --Hard
Parsing A Boolean Expression (Stack)
Remove Duplicate Letters (Monostack) --Tricky --IMP --Revise
Reverse Integer
Smallest Subsequence of Distinct Characters (Monostack)
Evaluate the Bracket Pairs of a String (Stack)
Binary Tree Right Side View (BFS)
Maximum Frequency Stack (Stack + Design) --HARD --Revise
Minimum Domino Rotations For Equal Row (Greedy) --Tricky --Revise
2 Keys Keyboard (DP)
Simplified Fractions
Smallest String With A Given Numeric Value (Greedy)
Ways to Split Array Into Three Subarrays (Prefix Sum + Binary Search) --Tricky --Revise** --IMP
Broken Calculator (Math)
Boats to Save People (Two Pointers)
Maximum Sum Circular Subarray (Kadane Algo) --IMP --Revise --Concept
Total Hamming Distance (Bit Manip) --IMP --Revise
Flatten Binary Tree to Linked List (Binary Tree) --IMP --TRICKY --HARD
Design a Stack With Increment Operation
Guess Number Higher or Lower II (DP) --Revise
Minimum Deletions to Make Character Frequencies Unique (Greedy) --Revise --**IMP
Continuous Subarray Sum (HashMap + Prefix Sum) --Logic similar to Subarray Sums Divisible by K
3Sum With Multiplicity (HashMap) --IMP --Revise
Count Triplets That Can Form Two Arrays of Equal XOR (Prefix Xor) --CONCEPT --IMP --Revise
Find the Longest Substring Containing Vowels in Even Counts (Bitmask + HashMap) --Concept
Longest Word in Dictionary (Trie)
LRU Cache (Double Linked List + HashMap) --Popular --Must Revise
Game of Life
Maximum Product After K Increments (Priority Queue)
Find Players With Zero or One Losses
Path Sum III (Subarray sum = k technique on Tree) --IMP
Can I Win (Bitmask DP) --Tight Constraints
Minimum Number of Operations to Reinitialize a Permutation
Shortest Path to Get All Keys (BFS + Bitmask) --CONCEPT --Revise
Groups of Special-Equivalent Strings (DSU + Implementation Heavy)
Minimum Falling Path Sum II (Grid DP)
Minimum Falling Path Sum (Grid DP)
First Missing Positive --IMP --Revise --HARD
Partition Array for Maximum Sum (DP)
Minimum Sideway Jumps (DP)
All Possible Full Binary Trees (DP) --Tricky --IMP
Number of Ways to Stay in the Same Place After Some Steps (DP)
Adding Spaces to a String
Number of Smooth Descent Periods of a Stock (DP)
Minimum Operations to Make the Array K-Increasing (Binary Search LIS variation) --CONCEPT --IMP --Tricky --Revise
Allocate Mailboxes (DP) --Tough --Revise --Concept
Best Sightseeing Pair (TreeSet/PriorityQueue/DP)
Number of Ways to Split a String (Combinatorics + Prefix Sum) --IMP --Revise
Minimum Cost to Connect Two Groups of Points (Bitmask DP) --Tricky Optimization --Tough
Change Minimum Characters to Satisfy One of Three Conditions --IMP --Tricky Brute Force
Path With Minimum Effort (Binary Search + DFS) --Concept
Heaters (Binary Search)
Most Profit Assigning Work (Greedy+Sorting) --Revise --IMP
Ways to Make a Fair Array (Prefix Sum)
Range Frequency Queries (Binary Search) --Revise --IMP --Concept
Find the Minimum Number of Fibonacci Numbers Whose Sum Is K (Greedy) --Revise
Minimum Average Difference (Prefix Sum)
Count Unguarded Cells in the Grid (Simulation)
Escape the Spreading Fire (Binary Search + Multi Source BFS) --CONCEPT --Implementation Heavy
Count Number of Homogenous Substrings
Shortest Unsorted Continuous Subarray (Prefix Max + Suffix Min) --CONCEPT
Different Ways to Add Parentheses (DnC DP) --Revise --IMP
Maximum Score From Removing Stones (PriorityQueue)
All O`one Data Structure
Word Subsets --IMP --REVISE --Tricky
Number of Substrings Containing All Three Characters (Sliding Window) --IMP --Revise
Longest Subarray of 1's After Deleting One Element
Remove All Adjacent Duplicates in String II (Stack)
Count Number of Nice Subarrays (Sliding Window) --IMP --REVISE --CONCEPT
132 Pattern (Prefix Min + TreeMap) --IMP --REVISE**
Flatten Nested List Iterator (Recursion)
Knight Probability in Chessboard (DP) --IMP
Count Sorted Vowel Strings
Permutations II (Backtracking) --IMP --REVISE
Corporate Flight Bookings (Partial Sum)
Shortest Path in Binary Matrix (BFS)
Queries on Number of Points Inside a Circle (Brute Force)
Rank Teams by Votes
RLE Iterator
Find Largest Value in Each Tree Row
Making A Large Island (DSU)
Delete Columns to Make Sorted II --Revise --Tricky
Check if Number is a Sum of Powers of Three
Maximum Bags With Full Capacity of Rocks
Minimum Lines to Represent a Line Chart
Sum of Total Strength of Wizards (Prefix Sum + Monotonic Stack) --IMP --HARD --Implementation Heavy
Ones and Zeroes (DP)
Minimize Malware Spread (DSU) --IMP --Revise
Longest Valid Parathesis (Stack) --IMP --Revise --CONCEPT
4Sum (Two Pointers) --IMP --Revise
Russian Doll Envelopes (Binary Search LIS) --V.IMP --Revise --Concept
Letter Tile Possibilities (Backtacking)
Flower Planting With No Adjacent (Graphs Coloring)
Triples with Bitwise AND Equal To Zero (Brute Force)
Minimum Area Rectangle (HashMap) --Revise --IMP
Reorder List (LinkedList)
Minimum Area Rectangle II (HashMap) --Revise --IMP
Partition List (LinkedList)
Rotate Image --IMP --Revise
Number of Dice Rolls With Target Sum (DP)
Maximum Length of a Concatenated String with Unique Characters (Backtracking)
Minimum Number of Work Sessions to Finish the Tasks (Bitmask DP)
Word Search II (Backtracking + Trie)
Maximum Product of Word Lengths (Bitmask)
Count Nodes Equal to Average of Subtree
Maximum Absolute Sum of Any Subarray (Kadanes)
Cutting Ribbons (Binary Search) (Premium Qs solved on binarysearch.com) --IMP --Revise
Break a Palindrome (Greedy) --IMP --Revise
Implement Trie (Prefix Tree) (Trie)
Replace Words (Trie)
Permutation Sequence (Greedy) --IMP --Revise
Factorial Trailing Zeroes (Math) --IMP --Revise
Sum Root to Leaf Numbers
Spiral Matrix
Set Matrix Zeroes --IMP --Tricky
Number of Good Ways to Split a String (Prefix and Suffix)
Restore The Array (DP)
Single Element in a Sorted Array (Binary Search) --V. IMP --Revise --Tricky
Lowest Common Ancestor of Deepest Leaves (Tree)
Strange Printer (DP) --V. HARD
Find Critical and Pseudo Critical Edges in Minimum Spanning Tree (Graphs) --CONCEPT --Revise
Avoid Flood in The City (Binary Search/TreeSet) --IMP --Tricky --Revise
Making File Names Unique
Number of Subsequences That Satisfy the Given Sum Condition (Two Pointers)
N-Queens (Backtracking)
N-Queens II (Backtracking)
Snakes and Ladders (BFS) --TRICKY
Minimum Window Substring (Sliding Window) --V.IMP --Revise --Popular
Cheapest Flights Within K Stops (Graphs) --IMP --Revise
Online Election (TreeMap)
Cat and Mouse II (Game Theory DP)
Insert Delete GetRandom O(1) - Duplicates allowed (Design) --Revise --IMP
Largest Values From Labels (Greedy)
Reorder Routes to Make All Paths Lead to the City Zero (Graphs)
Minimize Malware Spread II (Graphs+DSU) --Revise
Checking Existence of Edge Length Limited Paths ( Graphs MST + Sorting)
Loud and Rich (Graphs/DFS)
Minimum Cost Tree From Leaf Values (DP) --IMP --Revise
Regular Expression Matching (DP) --IMP --REVISE
Sum of Beauty in the Array (PrefixMin + Suffix Max)
Partition Array into Disjoint Intervals (PrefMin + Suffix Max)
Design Front Middle Back Queue (Deque Design)
Time Based Key-Value Store (Binary Search)
Find Median from Data Stream (Priority Queue) --V.IMP* --Revise
Sliding Window Median (2 TreeSets) --V.IMP --Revise
Longest String Chain (LIS DP)
Longest Happy String (Greedy/ PriorityQueue) --V.IMP --Revise
Boundary of Binary Tree (Tree) (Solved on LintCode) --IMP --Revise
Construct Binary Tree from Inorder and Postorder Traversal (Tree / DnC) --REVISE --V.IMP
Construct Binary Tree from Preorder and Inorder Traversal (Tree / DnC) --REVISE --V.IMP
Count and Say (DP / Simulation)
Construct Binary Search Tree from Preorder Traversal (Tree / DnC) --REVISE --V.IMP
Restore IP Addresses (Backtracking)
Largest BST Subtree (Tree) (Solved on binarysearch.com) --IMP --Revise
Binary Tree Cameras (Tree DP) --HARD --REVISE
Lexicographically Smallest Equivalent String (DSU) (Solved on binarysearch.com as String Equivalence Relations)
Prefix and Suffix Search (Trie) --CONCEPT --IMP
Search a 2D Matrix II (Matrix) --V.IMP --Revise
Kth Largest Element in an Array (QuickSelect) --IMP --Revise
Search Suggestions System (Trie) --Revise
Maximum Number of Events That Can Be Attended (Sweep Line) --Tricky --V.IMP
Maximum Number of Events That Can Be Attended II (Binary Search + DP)
Course Schedule III (Greedy) --Concept --HARD
Course Schedule IV (Graphs)
Fruit Into Baskets (Sliding Window)
Delete Nodes And Return Forest (Tree)
Reverse Pairs (Merge Sort)
Number of Longest Increasing Subsequence (DP) --V. IMP Revise
Random Pick with Weight (Randomized Algo -- Binary Search) --IMP --Revise
Serialize and Deserialize Binary Tree (BFS)
Parallel Courses II (Bitmask DP) --HARD
Longest Subarray of 1's After Deleting One Element (Prefix/SUffix Processing)
Largest Number (Sorting with Custom Comparator)
Maximum Score Of Spliced Array (Prefix Sum) --IMP --REVISE
Pacific Atlantic Water Flow (Graphs)
Stock Price Fluctuation (TreeMap)
Minimum Difference Between Largest and Smallest Value in Three Moves (Greedy) --IMP --**REVISE
Asteroid Collision (Stack) --Tricky Edge cases
Count Square Submatrices with All Ones (DP)
Odd Even Jump (DP + TreeMap) --IMP --Revise
Queue Reconstruction by Height (Sorting) --Tricky
Number of Submatrices That Sum to Target (Prefix Sum + HashMap)
Minimum Moves to Equal Array Elements II (Median)
Last Moment Before All Ants Fall Out of a Plank --CONCEPT
Count Submatrices With All Ones (DP) --HARD --TRICKY
Bulls and Cows
Single Number III (Bit Manipulation)
Maximum Gap (Bucket Approach) --CONCEPT --HARD
Longest Arithmetic Subsequence (LIS Type DP)
Vertical Order Traversal of a Binary Tree (DFS + HashMap)
Sum of Square Numbers (Math)
Maximum Product of Splitted Binary Tree (Tree DP)
Spiral Matrix IV
Number of People Aware of a Secret (DP) --HARD
Number of Increasing Paths in a Grid (DP)
Queries on a Permutation With Key (Fenwick Tree) --CONCEPT --IMP
Domino and Tromino Tiling (DP) --IMP
Shifting Letters
Minimum Time to Make Rope Colorful (Greedy)
Interleaving String (DP)
Minimum Possible Integer After at Most K Adjacent Swaps On Digits (Fenwick Tree + Greedy) --IMP --REVISE
Online Majority Element In Subarray (Segment Tree) --CONCEPT --REVISE
Design Circular Deque (Design) --IMP --Popular --Revise
Paint house III (DP)
Minimum Numbers of Function Calls to Make Target Array (Math/ Bit Manipulation)
Smallest Number in Infinite Set
Move Pieces to Obtain a String (Prefix Sum)
Jump Game VI (DP + Monotonic Queue) --CONCEPT --Tricky
Find Smallest Common Element in All Rows (TreeMap+HashSet) (Solved on binarysearch.com)
Maximum of Minimum Values in All Subarrays (MonoStack + Suffix Max) (Solved on GFG) --HARD --CONCEPT
01 Matrix (Multi-Source BFS)
Push Dominoes (Two Pointer) --IMP
Non-negative Integers without Consecutive Ones (Digit DP)
Count Unique Characters of All Substrings of a Given String --IMP
Kth Smallest Element in a Sorted Matrix (Binary Search and other approaches) --POPULAR --IMP --REVISE
Number of Nodes in the Sub-Tree With the Same Label
Minimum Number of Swaps to Make the Binary String Alternating --IMP
Check Completeness of a Binary Tree (BFS) --IMP
Even Odd Tree (BFS)
Number of Good Leaf Nodes Pairs (Tree)
Minimum Suffix Flips
String Compression II (DP) --HARD --Runtime Strict**
Selling Pieces of Wood (DP) --IMP
Maximize the Confusion of an Exam (Sliding Window)
Lexicographical Numbers (Backtracking)
Find the Winner of an Array Game (Simulation)
Max Sum of a Pair With Equal Sum of Digits
Query Kth Smallest Trimmed Number
Minimum Deletions to Make Array Divisible (GCD + Sorting)
Count of Range Sum (Fenwick Tree + Binary Search)
Minimum Swaps to Arrange a Binary Grid (Greedy) --IMP --REVISE
Get the Maximum Score (DP) --IMP
Find Kth Bit in Nth Binary String
Maximum Number of Non-Overlapping Subarrays With Sum Equals Target (Prefix Sum) (DP) (Greedy) --IMP
Recover Binary Search Tree (BST) --IMP --POPULAR
Can Convert String in K Moves (Greedy) --IMP
Count Substrings That Differ by One Character (Counting Problem) --IMP --CONCEPT
Minimum Insertions to Balance a Parentheses String (Stack) --HARD --TRICKY
Minimum Add to Make Parentheses Valid (Stack)
Find Longest Awesome Substring (Prefix Bitmask) --CONCEPT --IMP
Maximum Side Length of a Square with Sum Less than or Equal to Threshold (Sliding Window) (2D Prefix Sum + Binary Search)
Design Circular Queue
Sliding Puzzle (BFS) --IMPLEMENTATION HEAVY
Magnetic Force Between Two Balls (Binary Search) --IMP
Minimum Number of Days to Eat N Oranges (DP) --Tricky --Math
Reverse Linked List II
Find Latest Group of Size M (DSU) --Tricky --Unable to Implement without WA
Detect Cycles in 2D Grid (DSU)
Minimum Number of Days to Disconnect Island (DSU) --Observation Based
Number of Ways to Reorder Array to Get Same BST (Divide And Conquer) --CONCEPT --IMP --Revise
Number of Ways Where Square of Number Is Equal to Product of Two Numbers (Counting)
Find and Replace Pattern (HashMap)
Shortest Subarray to be Removed to Make Array Sorted (Two Pointer) --TRICKY --HARD
Count All Possible Routes (DP)
Count Unhappy Friends (Brute Force) --Bad problem
Check If String Is Transformable With Substring Sort Operations (Greedy) --IMP
Maximum Product Subarray (DP) --IMP --REVISE
Maximum Non Negative Product in a Matrix (DP) --IMP --REVISE
Split a String Into the Max Number of Unique Substrings (Backtracking)
Last Stone Weight II (DP) --Revise --V.IMP
My Calendar I (TreeMap/ Binary Search) --IMP --Revise
Strange Printer II (Topological Sort/ Check for DAG) --Tough To Come up With --Revise
Make Sum Divisible by P
Maximum Profit of Operating a Centennial Wheel
Throne Inheritance (Design)
Maximum Number of Achievable Transfer Requests (Bitmask) --IMP
Number of Different Subsequences GCDs (Math) --TRICKY --REVISE --CONCEPT
Maximum Number of Visible Points (Sliding Window + Geometry) --IMP --TRICKY --CONCEPT
Minimum One Bit Operations to Make Integers Zero (Bit Manipulation + DP) --HARD --TRICKY
Find Valid Matrix Given Row and Column Sums --Tricky
Alert Using Same Key-Card Three or More Times in a One Hour Period
Find Servers That Handled Most Number of Requests (TreeSet/BinarySearch + SweepLine) --REVISE --CONCEPT
Number of Times Binary String Is Prefix_Aligned --REVISE --TRICKY --IMP
Node With Highest Edge Score (Graphs)
Construct Smallest Number From DI String (Two Pointer + Greedy) --IMP
Count Special Integers ( Digit DP + Bitmask) --REVISE
Split Two Strings to Make Palindrome (Greedy) --IMP --REVISE --CONCEPT
Count Subtrees With Max Distance Between Cities (Graph + Bitmask) --IMP
Best Team With No Conflicts (DP) --IMP --Revise
Lexicographically Smallest String After Applying Operations (Brute Force)
Watering Plants II
Split Array into Consecutive Subsequences (Greedy + PriorityQueue) --IMP --Revise --Tricky
Find Peak Element (Binary Search)
Fancy Sequence (Linear Functions) --V. V. HARD --CONCEPT
Coordinate With Maximum Network Quality (Brute Force)
Number of Sets of K Non-Overlapping Line Segments (DP) --Revise
Minimum Number of Refueling Stops (Greedy/PQ) --Revise --V. IMP
Stamping The Sequence ( Greedy) --TOUGH --HEAVY GREEDY
Unique Paths III (Bitmask)
Accounts Merge
Maximum Sum BST in Binary Tree --V.IMP --REVISE
Count Nice Pairs in an Array
Unique Binary Search Trees (DnC DP)
Sort the Matrix Diagonally (Count Sort)
Kth Smallest Instructions (Greedy) --IMP --Revise
Number of Ways to Form a Target String Given a Dictionary (DP) --IMP --Revise
Shuffle an Array (Randomized Algo - Fisher Yates Shuffle Algorithm) --V.V.IMP
Strictly Palindromic Number
Maximum Rows Covered by Columns (Bitmask)
Maximum Number of Robots Within Budget (MonoQueue + Binary Search) --**V.IMP --Revise
Longest Nice Subarray (Sliding Window) --Revise
Number of Ways to Reach a Position After Exactly k Steps (DP)
Subarray With Elements Greater Than Varying Threshold (MonoStack) --Tricky --V IMP
The Number of Weak Characters in the Game (Sorting + Two Pointer + SuffixMax)
Longest Chunked Palindrome Decomposition (String Hashing) --TOUGH --Implementation Heavy
Longest Duplicate Substring (String Hashing + Binary Search) --V.IMP
Repeated DNA Sequences
Distinct Echo Substrings (String Hashing)
Maximum Length of Repeated Subarray (String Hashing + Binary Search)
Optimal Partition of String (Greedy)
Divide Intervals Into Minimum Number of Groups (SweepLine / PQ)
Longest Increasing Subsequence II (DP + Segment Tree) --IMP --CONCEPT
Bag of Tokens (Greedy + Two Pointer)
Pseudo-Palindromic Paths in a Binary Tree
Product of the Last K Numbers (Prefix Products) --CONCEPT --REVISE
Number of Ways to Wear Different Hats to Each Other (Bitmask DP) --Tricky --CONCEPT
Find Original Array From Doubled Array (Sorting + Two Pointer) --IMP
Palindrome Pairs --Implementation Heavy --Tight Constraint
Length of the Longest Alphabetical Continuous Substring
Reverse Odd Levels of Binary Tree (Tree)
Sum of Prefix Scores of Strings (Trie)
Find Duplicate File in System
Longest Subarray With Maximum Bitwise AND
Find All Good Indices (Prefix/Suffix)
Number of Good Paths (DSU+Sorting) --CONCEPT --IMP
Longest Arithmetic Subsequence of Given Difference (DP)
Maximum Sum of an Hourglass
Minimize XOR (Bit Manipulation + Greedy)
Maximum Deletions on a String (String Hashing + DP) --IMP
Longest Uploaded Prefix
Bitwise XOR of All Pairings (Bit Manipulation)
Number of Pairs Satisfying Inequality (Fenwick Tree) --IMP --Revise
Erect The Fence ( Geometry - Convex Hull) --IMP --Revise
Binary Search Tree to Greater Sum Tree (Tree)
Reaching Points (Greedy + Math) --IMP CONCEPT --HARD --Tricky
Find the Index of the First Occurrence in a String
Delete the Middle Node of a Linked List
Count Number of Distinct Integers After Reverse Operations
Sum of Number and Its Reverse
Count Subarrays With Fixed Bounds (Sliding Window) --CONCEPT --HARD
Minimum Difficulty of a Job Schedule (DP)
Top K Frequent Words (Min Heap)
Contains Duplicate III (Binary Seach/ TreeMap) --IMP
Image Overlap --IMP --CONCEPT
Single-Threaded CPU (Greedy) --V.IMP
Find XOR Sum of All Pairs Bitwise AND (Bit manipulation) --CONCEPT --IMP
Max Points on a Line (Geometry)
Words Within Two Edits of Dictionary
Destroy Sequential Targets
Next Greater Element IV (Monotstack + Binary Search + Segment Tree) --CONCEPT* --IMP
Most Popular Video Creator
Minimum Addition to Make Integer Beautiful (Greedy) --IMP --REVISE
Height of Binary Tree After Subtree Removal Queries (Euler Tour + Tree DP + Prefix Suffix) --V.V.IMP
Where Will the Ball Fall
Implement Magic Dictionary (Trie)
Minimum Genetic Mutation (BFS)
Orderly Queue (Greedy)
Maximum Sum of Distinct Subarrays With Length K (Fixed Sling Window)
Total Cost to Hire K Workers (Greedy) --IMP
Minimum Total Distance Traveled (DP)
Online Stock Span (MonoStack) --IMP --REVISE
Valid Sudoku --IMP
Odd Even Linked List
Reconstruct Itinerary (Euler Path of Graph) --V.IMP --REVISE
Minimum Rounds to Complete All Tasks (Math) ---Revise
Powerful Integers (Brute Force + Math)
Maximal Score After Applying K Operations
Make Number of Distinct Characters Equal
As Far from Land as Possible (Multi Source BFS) --IMP --REVISE
Maximize Score After N Operations (Bitmask DP)
Longest Path With Different Adjacent Characters (Tree DP) --IMP
Longest Well-Performing Interval (Prefix Sum) --V.IMP --*Tricky
Count the Number of Good Subarrays (Sliding Window) --V.IMP --Concept
Number of Valid Words for Each Puzzle (Bitmask/Submask Enumeration) --V.IMP --CONCEPT
Flip String to Monotone Increasing (DP)
Get Equal Substrings Within Budget (Binary Search + Fixed SLiding Window)
Apply Bitwise Operations to Make Strings Equal (Bit Operations Observation)
Minimum Cost to Split an Array (DP + Preprocessing) --IMP --REVISE
Find Closest Node to Given Two Nodes ( Graphs)
Data Stream as Disjoint Intervals (Binary Search) --IMP --REVISE
Freedom Trail (DP) --CONCEPT
Count the Number of Fair Pairs (Sorting + Binary Search) --V.IMP -Revise*
Substring XOR Queries (Bit Manipulation + Tricky Observation) --Revise --CONCEPT
Subsequence With the Minimum Score (Prefix and Suffix) --IMP. CONCEPT
Maximum Number of Consecutive Values You Can Make (Greedy/ Observation) --IMP --Tricky CONCEPT
Subarrays with K Different Integers (Sliding Window) --IMP
Pancake Sorting (Observation and Logic) --Observation
Number of Ways to Divide a Long Corridor (Counting/ Math) --IMP
Divide Array in Sets of K Consecutive Numbers (Greedy) --IMP
Check Knight Tour Configuration
The Number of Beautiful Subsets (Backtracking)
Smallest Missing Non-negative Integer After Operations (Math) --V. IMP
Design Underground System (Design)
Maximum Value of K Coins From Piles (DP) --Concept
Shortest Bridge (DFS + BFS) --IMP
Put Marbles in Bags (Heaps/Greedy) --Tricky --Revise
All Nodes Distance K in Binary Tree (Graphs) --IMP
Find All Duplicates in an Array (Cycle Sort) --IMP --Concept --Revise
Minimum Speed to Arrive on Time (Binary Search)
Minimum Number of Removals to Make Mountain Array (DP) --IMP --Concept
Dinner Plate Stacks (Stacks + TreeSet) --IMP --Revise
Maximum Performance of a Team (Greedy) --V.IMP --Revise

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