Interview Questions

1. Array  
   • K-Concatenation
   • Maximum Contiguous Circular Subarray Sum
   • Find Subarray With Given Sum
   • Equilibrium Index Of An Array
   • Maximum Sum Increasing Subsequence
   • Convert Array Into Zig Zag Fashion
   • Find A Pair With The Given Difference
   • Chocolate Distribution Problem
   • Minimum Number of Platforms Required for a Railway/Bus Station
   • Trapping Rain Water
   • Stock Buy Sell to Maximize Profit
   • Inplace Rotate Square Matrix By 90 Degrees
   • Find k Pairs With Smallest Sums In Two Arrays
   • Search An Element In A Sorted And Rotated Array
   • Given A Sorted And Rotated Array, Find If There Is A Pair With A Given Sum
   • Maximum Sum i*arr[i] Among All Rotations Of A Given Array
   • Rearrange Positive And Negative Numbers In O(n) Time And O(1) Extra Space
   • Three Way Partitioning Of An Array Around A Given Range
   • Maximum Length Bitonic Subarray
   • Largest Subarray With Equal Number Of 0S And 1S
   • Maximum Product Subarray
   • Counting Inversions In An Array
   • Segregate 0s and 1s In An Array
   • Sort An Array Of 0S, 1S And 2S
   • Merging Intervals
   • Maximum Profit By Buying And Selling A Share At Most Twice
   • Maximum Profit By Buying And Selling A Share At Most K Times
   • Maximum Difference Between Two Elements
   • Minimize The Maximum Difference Between The Heights
   • Move All Zeroes To End Of Array
   • Minimum Swaps Required To Bring All Elements Less Than Or Equal To k Together
   • Largest Sum Subarray With At-Least k Numbers
   • Form Minimum Number From Given Sequence
   • Find The Smallest Positive Integer Value That Cannot Be Represented As Sum Of Any Subset Of A Given Array
   • Generate All Possible Sorted Arrays From Alternate Elements Of Two Given Sorted Arrays
   • Next Permutation
   • Given An Array Arr[], Find The Maximum J- I Such That Arr[j] > Arr[i]
   • Maximum Sum of 3 Non-Overlapping Subarrays
   • Number Of Subarrays With Maximum Values In Given Range
   • Print All Possible Combinations Of R Elements In A Given Array Of Size N
   • Longest Subarray Sum Divisible K
   • Find Minimum Number Of Merge Operations To Make An Array Palindrome
   • Reorder An Array According To Given Indexes
   • Maximum Score
   • Rearrange An Array In Maximum Minimum Form | Set 2 (O(1) Extra Space)
   • Arrange Given Numbers To Form The Biggest Number
   • Space Optimization Using Bit Manipulations
   • MO’s Algorithm (Query Square Root Decomposition)
   • Amazon Interview Question for Software Engineer / Developers
2. Searching & Sorting  
   • Majority Element
   • Searching Array Adjacent Differ K
   • Find A Repeating And A Missing Number
   • Ceiling In A Sorted Array
   • Find A Pair With The Given Difference
   • Find Four Elements That Sum To A Given Value Set 2
   • Median Of Two Sorted Arrays Of Different Sizes
   • Maximum Sum Such That No Two Elements Are Adjacent
   • Find Common Elements Three Sorted Arrays
   • Count Triplets With Sum Smaller That A Given Value
   • Merge Two Sorted Arrays O1 Extra Space
   • 3 Way Quicksort Dutch National Flag
   • Counting Sort
   • Radix Sort
   • How To Efficiently Sort A Big List Dates In 20S
   • Median Of Stream Of Integers Running Integers
   • Make Array Elements Equal Minimum Cost
   • Check Reversing Sub Array Make Array Sorted
   • Print All Subarrays With 0 Sum
   • Nearly Sorted Algorithm
   • A Product Array Puzzle
   • Find Number Pairs Xy Yx
   • Find Duplicates In On Time And Constant Extra Space
   • Insert In Sorted And Non Overlapping Interval Array
   • Sort Array According Count Set Bits
   • Minimum Swaps To Make Two Array Identical
   • Find Largest Multiple 3 Array Digits Set 2 Time O1 Space
   • Permute Two Arrays Sum Every Pair Greater Equal K
   • Find Pair With Greatest Product In Array
   • Minimum Number Swaps Required Sort Array
3. String  
   • Print Words Together Set Characters
   • Generate All Binary Strings From Given Pattern
   • Smallest Window Contains Characters String
   • Count Ways Increase Lcs Length Two Strings One
   • Given A Sequence Of Words Print All Anagrams Together
   • Anagram Substring Search Search Permutations
   • Check Two Strings K Anagrams Not
   • Check Binary Representations Two Numbers Anagram
   • Longest Palindromic Substring Set 2
   • Find The Smallest Window In A String Containing All Characters Of Another String
   • Permutation and Palindrome
   • Make Largest Palindrome Changing K Digits
   • Lexicographically First Palindromic String
   • Longest Non Palindromic Substring
   • String Merging
   • Find Kth Character Of Decrypted String
   • Count Words Whose Th Letter Either 1 Th Th I1 Th Letter Given Word
   • Find Number Distinct Palindromic Sub Strings Given String
   • Print All Distinct Characters Of A String In Order 3 Methods
   • Count Total Anagram Substrings
   • Min Flips Of Continuous Characters To Make All Characters Same In A String
   • Count Binary Strings K Times Appearing Adjacent Two Set Bits
   • Binary Representation Next Greater Number Number 1S 0S
   • Print Longest Common Sub Sequences Lexicographical Order
   • Print Shortest Common Supersequence
   • Given Two Strings Find First String Subsequence Second
   • Find Largest Word Dictionary Deleting Characters Given String
   • Search A Word In A 2D Grid Of Characters
   • Number Subsequences Form Ai Bj Ck
   • Find Number Times String Occurs Given String
   • Count Distinct Subsequences
   • Find Patterns 101 Given String
   • Given A String Find Its First Non Repeating Character
   • Rearrange A String So That All Same Characters Become At Least D Distance Away
   • Recursively Remove Adjacent Duplicates Given String
   • Wildcard Character Matching
   • Lexicographic Rank Of A String
   • Print Number Ascending Order Contains 1 2 3 Digits
   • Given Sorted Dictionary Find Precedence Characters
   • Find Excel Column Name Given Number
   • Find The Longest Substring With K Unique Characters In A Given String
   • Function To Find Number Of Customers Who Could Not Get A Computer
   • Check Given Sentence Given Set Simple Grammer Rules
   • Length Of The Longest Valid Substring
   • Print Ways Break String Bracket Form
   • Print Concatenation Of Zig Zag String Form In N Rows
   • Searching For Patterns Set 2 Kmp Algorithm
   • Transform One String To Another Using Minimum Number Of Given Operation
   • Repeated Subsequence Length 2
   • Check If Two Given Strings Are Isomorphic To Each Other
   • Find Given String Can Represented Substring Iterating Substring N Times
   • Recursively Print All Sentences That Can Be Formed From List Of Word Lists
   • Searching For Patterns Set 3 Rabin Karp Algorithm
   • Number of subsequences in a string divisible by n
4. Matrix  
   • Zigzag Or Diagonal Traversal Of Matrix
   • Create A Matrix With Alternating Rectangles Of 0 And X
   • Print Elements Sorted Order Row Column Wise Sorted Matrix
   • Inplace Rotate Square Matrix By 90 Degrees
   • Find Number Of Islands
   • Given Matrix O X Replace O X Surrounded X
   • Validity Of A Given Tic Tac Toe Board Configuration/+
   • Given Matrix O X Find Largest Subsquare Surrounded X
   • Rotate Matrix Elements
   • Find Common Element Rows Row Wise Sorted Matrix
   • Maximum Size Rectangle Binary Sub Matrix 1S
   • Common Elements In All Rows Of A Given Matrix
   • Find A Specific Pair In Matrix
   • Find Orientation Of A Pattern In A Matrix
   • Shortest Path In A Binary Maze
   • Inplace Rotate Square Matrix By 90 Degrees
   • Kth Smallest Element In A Row Wise And Column Wise Sorted 2D Array Set 1
   • A Boolean Matrix Question
   • Search A Word In A 2D Grid Of Characters
5. BackTracking  
   • Backtracking Set 1 The Knights Tour Problem
   • Backttracking Set 2 Rat In A Maze
   • Backtracking Set 7 Suduku
   • Remove Invalid Parentheses
   • Word Break Problem Using Backtracking
   • Print Palindromic Partitions String
   • Find Shortest Safe Route In A Path With Landmines
   • Combinational Sum
   • Partition Set K Subsets Equal Sum
   • Longest Possible Route In A Matrix With Hurdles
   • Backtracking Set 8 Solving Cryptarithmetic Puzzles
   • Match A Pattern And String Without Using Regular Expressions
   • Find If There Is A Path Of More Than K Length From A Source
   • Backtracking Set 7 Hamiltonian Cycle
   • Tug Of War
   • Find Maximum Number Possible By Doing At Most K Swaps
   • Find Paths From Corner Cell To Middle Cell In Maze
   • Arithmetic Expressions
   • Crossword Puzzle
6. Greedy  
   • Greedy Algorithms Set 1 Activity Selection Problem
   • Job Sequencing Problem Set 1 Greedy Algorithm
   • Greedy Algorithm Egyptian Fraction
   • Fractional Knapsack Problem
   • Greedy Algorithm To Find Minimum Number Of Coins
   • Dynamic Programming Set 20 Maximum Length Chain Of Pairs
   • Find Minimum Time To Finish All Jobs With Given Constraints
   • Job Sequencing Using Disjoint Set Union
   • Minimum Sum Two Numbers Formed Digits Array 2
   • Find Smallest Number With Given Number Of Digits And Digit Sum
   • Minimum Sum Absolute Difference Pairs Two Arrays
   • Maximize Sum Consecutive Differences Circular Array
   • Paper Cut Minimum Number Squares
   • Lexicographically Smallest Array K Consecutive Swaps
   • Rearrange Characters String No Two Adjacent
   • Find Maximum Height Pyramid From The Given Array Of Objects
   • Minimum Cost For Acquiring All Coins With K Extra Coins Allowed With Every Coin
   • Find Maximum Sum Possible Equal Sum Three Stacks
   • Maximize Array Sun After K Negation Operations
   • Minimum Cost Cut Board Squares
   • Minimize Cash Flow Among Given Set Friends Borrowed Money
   • Minimum Edges Reverse Make Path Source Destination
7. Dynamic Programming  
   • Ugly Numbers
   • Super Ugly Number Number Whose Prime Factors Given Set
   • Maximum Size Sub Matrix With All 1S In A Binary Matrix
   • Dynamic Programming Subset Sum Problem
   • Minimum Number Of Jumps To Reach End Of A Given Array
   • Dynamic Programming Set 15 Longest Bitonic Subsequence
   • Maximum Sum Bi Tonic Sub Sequence
   • Lcs Longest Common Subsequence Three Strings
   • Friends Pairing Problem
   • Dynamic Programming Building Bridges
   • Dynamic Programming Set 18 Partition Problem
   • Count Number Of Ways To Partition A Set Into K Subsets
   • Dynamic Programming Set 12 Longest Palindromic Subsequence
   • Dynamic Programming Set 11 Egg Dropping Puzzle
   • Dynamic Programming Set 21 Box Stacking Problem
   • Dynamic Programming Set 24 Optimal Binary Search Tree
   • Dynamic Programming Set 28 Minimum Insertions To Form A Palindrome
   • Dynamic Programming Set 36 Cut A Rope To Maximize Product
   • Dynamic Programming Set 31 Optimal Strategy For A Game
   • Dynamic Programming Set 32 Word Break Problem
   • Mobile Numeric Keypad Problem
   • Find Number Of Solutions Of A Linear Equation Of N Variables
   • Count Number Ways Tile Floor Size N X M Using 1 X M Size Tiles
   • Count Number Binary Strings Without Consecutive 1S
   • Painters Partition Problem
   • Check Whether A Given String Is An Interleaving Of Two Other Given Strings Set 2
   • Wildcard Pattern Matching
   • Probability Knight Remain Chessboard
   • Two Water Jug Puzzle
   • Dynamic Programming Set 18 Word Wrap
   • Largest Sum Subarray Least K Numbers
   • Find Water In A Glass
   • Remove Minimum Elements Either Side 2Min Max
   • Number Subsequences Form Ai Bj Ck
   • Unbounded Knapsack Repetition Items Allowed
   • Length Of The Longest Valid Substring
   • Dynamic Programming Set 37 Boolean Parenthesization Problem
   • Count Possible Decodings Given Digit Sequence
   • Perfect Sum Problem Print Subsets Given Sum
   • Vertex Cover Problem Set 2 Dynamic Programming Solution Tree
   • Longest Even Length Substring Sum First Second Half
   • Count Possible Ways To Construct Buildings
   • Bitmasking And Dynamic Programming Set 1 Count Ways To Assign Unique Cap To Every Person
   • Longest Repeating Subsequence
   • Longest Common Increasing Subsequence Lcs Lis
   • Find If String Is K Palindrome Or Not
   • Minimum Sum Path 3 D Array
   • Count Distinct Subsequences
   • Shortest Uncommon Subsequence
   • Temple Offerings
   • Highway Billboard Problem
   • Maximum Sum Alternating Subsequence Sum
   • Minimum Maximum Values Expression
   • Minimum And Maximum Values Of An Expression With * And +
8. Stacks & Queues  
   • Implement Two Stacks In An Array
   • Design A Stack With Find Middle Operation
   • Efficiently Implement K Stacks Single Array
   • Implement Stack Using Priority Queue Or Heap
   • Stack Set 2 Infix To Postfix
   • The Celebrity Problem
   • Iterative Tower Of Hanoi
   • Design And Implement Special Stack Data Structure
   • Find The Maximum Of Minimums For Every Window Size In A Given Array
   • Length Of The Longest Valid Substring
   • Find Expression Duplicate Parenthesis Not
   • Lru Cache Implementation
   • Efficiently Implement K Queues Single Array
   • Find A Tour That Visits All Stations
   • Minimum Time Required So That All Oranges Become Rotten
   • Sum Minimum Maximum Elements Subarrays Size K
   • Stack Permutations Check If An Array Is Stack Permutation Of Other
   • Count Natural Numbers Whose Permutation Greater Number
   • Sort A Stack Using Recursion
   • Stack Set 4 Evaluation Postfix Expression
   • Queue Based Approach For First Non Repeating Character In A Stream
9. LinkedList  
   • Given Only A Pointer To A Node To Be Deleted In A Singly Linked List How Do You Delete It
   • Find First Non Repeating Character Stream Characters
   • Nth Node From The End Of A Linked List
   • Detect And Remove Loop In A Linked List
   • Write A Function To Get The Intersection Point Of Two Linked Lists
   • Remove Duplicates From An Unsorted Linked List
   • Merge Sort For Linked List
   • Delete Nodes Which Have A Greater Value On Right Side
   • Segregate Even And Odd Elements In A Linked List
   • Sum Of Two Linked Lists
   • Find A Triplet From Three Linked Lists With Sum Equal To A Given Number
   • Flattening A Linked List
   • Sort A Linked List Of 0S 1S Or 2S
   • Flatten A Linked List With Next And Child Pointers
   • Quicksort On Singly Linked List
   • A Linked List With Next And Arbit Pointer
   • Point To Next Higher Value Node In A Linked List With An Arbitrary Pointer
   • Rearrange A Given Linked List In Place
   • Select A Random Node From A Singly Linked List
   • Linked List In Zig Zag Fashion
   • Sort Linked List Already Sorted Absolute Values
   • Merge K Sorted Linked Lists
   • Flatten A Multi Level Linked List Set 2 Depth Wise
   • Subtract Two Numbers Represented As Linked Lists
   • Find Pair Given Sum Sorted Singly Linked Without Extra Space
   • Multiply Two Numbers Represented Linked Lists
   • Merge Two Sorted Lists Place
   • Rotate Linked List Block Wise
   • Josephus Circle Using Circular Linked List
   • Count Triplets Sorted Doubly Linked List Whose Sum Equal Given Value X
   • Sort Biotonic Doubly Linked List
10. Generic Trees  
    • Check Mirror N Ary Tree
    • Serialize Deserialize N Ary Tree
    • Immediate Smaller Element N Ary Tree
    • Second Largest Element N Ary Tree
    • Node Maximum Sum Immediate Children N Ary Tree
    • Given N Ary Tree Count Number Nodes Number Children Parent
    • Construct Full K Ary Tree Preorder Traversal
    • Creating Tree Left Child Right Sibling Representation
    • Left Child Right Sibling Representation Tree
    • Longest Path Undirected Tree
    • Amazon Interview Question for Software Engineer in Tests
    • Diameter N Ary Tree
11. Binary Trees  
    • Clone Binary Tree Random Pointers
    • Count Subtress Sum Given Value X
    • Inorder Tree Traversal Without Recursion
    • Inorder Tree Traversal Without Recursion And Without Stack
    • Morris Traversal For Preorder
    • Iterative Postorder Traversal
    • Diagonal Traversal Of Binary Tree
    • Print Binary Tree Vertical Order
    • Boundary Traversal Of Binary Tree
    • Perfect Binary Tree Specific Level Order Traversal
    • Construct A Special Tree From Given Preorder Traversal
    • Construct Tree From Ancestor Matrix
    • Construct Ancestor Matrix From A Given Binary Tree
    • Construct A Binary Tree From Parent Array Representation
    • Create Doubly Linked List Ternary Ree
    • In Place Convert A Given Binary Tree To Doubly Linked List
    • Convert A Given Tree To Sum Tree
    • Change A Binary Tree So That Every Node Stores Sum Of All Nodes In Left Subtree
    • Convert A Binary Tree To A Circular Doubly Link List
    • Convert Tree Forest Even Nodes
    • Lowest Common Ancestor Binary Tree Set 1
    • Find Distance Between Two Nodes Of A Binary Tree
    • Print Common Nodes Path Root Common Ancestors
    • Root To Leaf Path Sum Equal To A Given Number
    • Populate Inorder Successor For All Nodes
    • Connect Nodes At Same Level With O1 Extra Space
    • Connect Nodes At Same Level
    • Foldable Binary Trees
    • Maximum Width Of A Binary Tree
    • Double Tree
    • Find The Maximum Sum Path In A Binary Tree
    • Vertical Sum In A Given Binary Tree
    • Find Next Right Node Of A Given Key
    • Deepest Left Leaf Node In A Binary Tree
    • Connect Leaves Doubly Linked List
    • Print Left View Binary Tree
    • Custom Tree Problem
    • Reverse Alternate Levels Binary Tree
    • Print Nodes Distance K Given Node Binary Tree
    • Find Distance Between Two Nodes Of A Binary Tree
    • Diagonal Sum Binary Tree
    • Tilt Binary Tree
    • Find Height Binary Tree Represented Parent Array
    • Remove Nodes Root Leaf Paths Length K
    • Find Maximum Path Sum In A Binary Tree
    • Expression Tree
    • Width Binary Tree Set 1
    • Reverse Tree Path
    • Dynamic Programming Trees Set 2
    • Serialize Deserialize Binary Tree
    • Find Maximum Path Sum Two Leaves Binary Tree
    • Find Height Of A Special Binary Tree Whose Leaf Nodes Are Connected
12. Binary Search Trees  
    • Construct Bst From Given Preorder Traversa
    • Binary Tree To Binary Search Tree Conversion
    • In Place Convert Bst Into A Min Heap
    • Construct Bst Given Level Order Traversal
    • Check For Identical Bsts Without Building The Trees
    • Kth Largest Element In Bst When Modification To Bst Is Not Allowed
    • Kth Smallest Element In Bst Using O1 Extra Space
    • Check Whether Bst Contains Dead End Not
    • Merge Two Balanced Binary Search Trees
    • Fix Two Swapped Nodes Of Bst
    • Find If There Is A Triplet In Bst That Adds To 0
    • Find A Pair With Given Sum In Bst
    • Remove Bst Keys Outside The Given Range
    • Add Greater Values Every Node Given Bst
    • Inorder Predecessor Successor Given Key Bst
    • Given N Appointments Find Conflicting Appointments
    • Data Structure For Future Reservations For A Single Resource
    • Count Bst Subtrees That Lie In Given Range
    • Replace Every Element With The Least Greater Element On Its Right
    • Find Closest Element Binary Search Tree
    • Sum K Smallest Elements Bst
    • Maximum Element Two Nodes Bst
    • Binary Search Tree Insert Parent Pointer
    • Largest Bst Binary Tree Set 2
    • Leaf Nodes Preorder Binary Search Tree
    • Find Median Bst Time O1 Space
    • Avl Tree Set 1 Insertion
    • Avl Tree Set 2 Deletion
13. Order Statistics & Heap & Hash  
    • K Largest(or Smallest) Elements In An Array | Added Min Heap Method
    • Next Greater Element
    • Kth Smallest/Largest Element In Unsorted Array
    • Sliding Window Maximum (Maximum Of All Subarrays Of Size K)
    • Find The Smallest Positive Number Missing From An Unsorted Array
    • Find The Maximum Repeating Number in O(n) Time And O(1) Extra Space
    • Online Algorithm For Checking Palindrome In A Stream
    • Kth Largest Element In A Stream
    • K-th Smallest Element After Removing Some Integers From Natural Numbers
    • Find Surpasser Count Of Each Element In Array
    • A Pancake Sorting Question
    • Choose k Array Elements Such That Difference Of Maximum And Minimum Is Minimized
    • Find k Closest Elements To A Given Value
    • Tournament Tree And Binary Heap
    • Connect N Ropes with Minimum Cost
    • Design An Efficient Data Structure For Given Operations
    • Cuckoo Hashing – Worst Case O(1) Lookup!
    • Find Number Of Employees Under Every Manager
    • Find Itinerary From A Given List Of Tickets
    • Check If An Array Can Be Divided Into Pairs Whose Sum Is Divisible By K
    • Find The Length Of Largest Subarray With 0 Sum
    • Count Distinct Elements In Every Window Of Size K
    • Design A Data Structure That Supports Insert, Delete, Search And GetRandom In Constant Time
    • Length of The Largest Subarray With Contiguous Elements
    • Group Shifted String
    • Palindrome Substring Queries
    • Find Four Elements A, B, C and D in an array such that A+B = C+D
    • Subarrays With Distinct Elements
    • Find Recurring Sequence In A Fraction
    • K Maximum Sum Combinations From Two Arrays
14. Graphs  
    • Roads and Libraries
    • Journey to the Moon
    • Even Tree
    • Course Schedule II
    • Mancunian And Liverbird Go Bar Hopping
    • Cheapest Flights Within K Stops
    • Dhoom 4
    • Monk And The Islands
    • Connected Horses
    • We Are On Fire
    • Mrinal And Three Musketeers
    • Efficient Network
    • Mr President
    • Chocolate Journey
    • Minimizing Path Cost
    • Oliver And The Game
    • Madmax
    • Friend Circles Problem
    • Strongly Connected Components
    • Minimum Number Of Trials To Reach From Source Word To Destination Word
    • Longest Path in a Directed Acyclic Graph
    • Find A Mother Vertex In A Graph
    • Count All Possible Paths Between Two Vertices
    • Water Jug Problem Using Bfs
    • Detect Cycle In An Undirected Graph
    • Detect Cycle in a Directed Graph
    • Snake and Ladder Problem
    • Given A Sorted Dictionary Of An Alien Language, Find Order Of Characters
    • Print All Jumping Numbers Smaller Than Or Equal To A Given Value
    • Optimal Read List Given Number Days
    • Count Number Of Trees In A Forest
    • Construct Binary Palindrome By Repeated Appending And Trimming
    • Find Eventual Safe States
    • Madmax
    • Equal
    • Even Tree
15. Bit Manipulation  
    • Find the two non-repeating elements in an array of repeating elements
    • Count set bits in an integer
    • Find the Number Occurring Odd Number of Times
    • Check if a number is Bleak
    • Copy set bits in a range
    • Write an Efficient Method to Check if a Number is Multiple of 3
    • Find position of the only set bit
    • Binary representation of a given number
    • Write an Efficient C Program to Reverse Bits of a Number
    • Count number of bits to be flipped to convert A to B
    • Count total set bits in all numbers from 1 to n
    • Swap two nibbles in a byte
    • Find the element that appears once
    • Program to find whether a no is power of two
    • Sum of bit differences among all pairs
    • Generate n-bit Gray Codes
    • Josephus problem
    • A Boolean Array Puzzle
    • Swap all odd and even bits
    • Calculate 7n/8 without using division and multiplication operators
16. Maths  
    • Euclidean algorithms (Basic and Extended)
    • Prime Factorization using Sieve O(log n) for multiple queries
    • Fermat’s Last Theorem
    • Matrix Exponentiation
    • Chinese Remainder Theorem
    • Birthday Paradox
    • Program for nth Catalan Number
    • Pollard’s Rho Algorithm for Prime Factorization
    • Euler’s Totient Function
    • Sieve of Eratosthenes in 0(n) time complexity
17. Geometry  
    • Orientation of 3 ordered points
    • How to check if two given line segments intersect?
    • Convex Hull | Set 1 (Jarvis’s Algorithm or Wrapping)
    • Find Simple Closed Path for a given set of points
    • Convex Hull | Set 2 (Graham Scan)
    • Quickhull Algorithm for Convex Hull
    • Closest Pair of Points | O(nlogn) Implementation
    • The Skyline Problem using Divide and Conquer algorithm
    • Given n line segments, find if any two segments intersect
    • Line Sweep Technique
    • Line Intersection using Bentley Ottmann Algorithm
    • Points Inside A Polygon 
18. Trie  
    • Sorting array of strings (or words) using Trie | Set-2 (Handling Duplicates)
    • Word Break Problem
    • Given a sequence of words, print all anagrams together
    • Implement a Phone Directory
    • Print all words matching a pattern in CamelCase Notation Dictonary
    • Print unique rows in a given boolean matrix
    • Count of distinct substrings of a string using Suffix Trie
19. Union Find  
    • Union Find
    • Disjoint Set (Or Union-Find) | Set 1 (Detect Cycle in an Undirected Graph)