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1. System Design Questions
2. Java OOP Concepts
3. C++ Concepts
4. Operating System Concepts
5. Reading-References
6. Algorithms and Data Structures

Large scale system design and object oriented design questions and topics

1. Keywords To Remember
2. Infrastructure Design Questions
3. System Design Questions
4. Object Oriented Design Questions
5. External References

Short sample programs to demonstrate the inbuilt object oriented concepts in Java language.

• Generics
• Equality
• String Representation of Object
• Hash code of Object
• Dynamic array
• Iterable
• Comparable
• assert
• Comparator
• Immutability

Short sample program to demonstrate C++ language basics

• Smart pointers
• move semantics
• move constructor
• move assignment
• enums & enum class
• Random numbers

• Synchronization
  • Simple producer consumer with busy wait, mutex in C++Link
  • Simple producer consumer withcondition variable, condition variable in C++Link
• File IO
  • Print all lines which contain a given patternLink
• Memory Management
  • Implement alignedmalloc() andfree()Link
  • Implementmalloc() andfree()Link
• Hash table implementation
  • Implement elementary hash table in C++Link
  • Hash table implementation in C++ using STLInspiration  Link

• Prefix Hash tree
  • Prefix Hash Tree: An Indexing Data Structure over Distributed Hash Tableshttps://www.eecs.berkeley.edu/~sylvia/papers/pht.pdf -
• Distributed Hash table
  • • https://en.wikipedia.org/wiki/Distributed_hash_table
• Suffix tree
  • Compressed Trie, used in pattern searching, hard algohttps://en.wikipedia.org/wiki/Suffix_tree
• Hash Functions
  • djb2

1. Google CodeJam
2. Algorithms
3. LeetCode

1. Google Code Jam 2018
2. Google Code Jam 2020

Princeton AlgorithmsPart 1 andPart2

• A general approach to backtracking questions (Subsets, Permutations, Combination Sum)Link
• A summary: how to use bit manipulation to solve problems easily and efficientlyLink

• Rearrange odd even elements in a linked list.C++
• Linked ListJava
• Alternating SplitJava
• Sort linked list
  • Simple methodC++
  • Using merge sortC++
• Clone list with random pointersC++
• Linked List implementation
  • Push, append, delete, pop, clone listC

• Dynamic StackJava
• StackOfStringsJava

• CircularQueueJava
• LinkedQueueJava
• DequeJava
• RandomizedQueueJava

• Max QueueJava
• Min QueueJava

• Binary tree
  • Recursive Preorder, inorder, postorder, height, diameterC++
• Construct balanced binary treeC++
• Find longest increasing path in binary treeC++
• Find longest increasing path in n-ary treeC++
• Find next right node in binary treeC++
• Count all possible distinct sums paths top-down in a binary tree.C++

• Binary Search Tree
  • Java
  • Recursive insert, search, construct balanced treeC++
  • Iterative insert, searchC++
• Interval Search TreeJavaC++

• Quick FindJava
• Quick UnionJava
• Weighted Quick UnionJava
• Weighted Quick Union with Path compressionJava
• Percolation ProblemJava

• Find the celebrity in room.C++
• Graph
  • Representation using STL, BFS, DFSC++

• Parse decimal, hexdecimal, octal from a file and output to another.C++
• Check if two strings are isomorphic.C++
• Find first unique character in a string.C++
• String sorting
  • Using trie data structureJava
• Auto Completion search
  • Using trieJava
• English word meaning dictionary
  • Using trieJava
• Longest Common Prefix
  • Using trieJava
• Pattern Searching
  • Using trie of all suffixJava
• Word Break problem
  • Using trie, recursive algorithmJava
• KMP Pattern searching
  • Search pattern in textJava
• Remove characters from a first string which are present in other stringC  C++<<<<<<< HEAD=======
• Interleaved string
  • Print interleaved string of 2 stringsC++
  • Find if a string is interleaved of two other stringsC++

Add disjoint set and interleaved string

• Spell checker.C++
• Trie data structure.Java

• Continuous onesJava
• Infections over a distanceJava
• 8 PuzzleJava
• Maximum sum rectangle in a 2D matrixC++

• Insertion sort (generic)JavaC++
• Selection sort (generic)Java
• Shell sort (generic)Java
• Merge sort (generic)JavaC++
• Bottom Up Merge (generic)Java
• Quicksort (generic)JavaC++
• 3-way Quicksort (generic)Java
• Dutch national flag problemC++
• Merge intervalsC++
• Meeting roomsC++

• Find peak elementC++
• Search in rotated arrayC++
• Search in a 2D matrixC++
• Find start and end of a range in a sorted arrayC++
• Find kth largest element
  • Using min heapC++
  • Using max heapC++
  • Using STL iterator and algorithmC++
  • Using quick select algorithmC++
• Binary Search
  • IterativeC++
  • RecursiveC++
  • C++ STLC++

• Word Break problem
  • Recursive algorithm, using trieJava
• Longest Common Subsequence
  • Naive, top-down, bottom up tabulation, LCS string, LCS of 3 stringsJava
  • Naive recursion, top-down memoization, space optimized, bottom up tabulationC++
• Shortest Common Supersequence
  • Using DPJava
  • Using LCSJava
• Longest Common Substring
  • Recursive, bottom-up, space optimized, print substring, without repeating charactersJava
• Longest Common Substring in array
  • Stem in an array of stringsJava
• Subsequence variants: Repeated Subsequence
  • top-down, naive recursion, print sequenceJava
• Levenshtein distance / Edit DistanceJava
• Largest sqaure submatrix of 1sJava
• Min cost path from top right to bottom down in matrixJava
• Maximum value of expressionJava
• Subset sum partitionJava
• Three PartitionJava
• Rod CuttingJava
• Rod Cutting ProductJava
• Coin Change - Minimum number of coins
  • Java
  • C++
• Coin Change WaysJava
• Binary String with no consecutive 1sJava
• Word BreakJava
• Word Break using trieJava
• Array Adjustment costJava
• No of ways for dice throwsJava
• Wildcard MatchingJava
• Tripping Rain WaterJava
• Jump GameC++
• Length of Longest Increasing SubsequenceC++

• Activity SelectionJava
• Activity Sequencing
  • Naive algorithmJava
  • Using union-findJava

• kth element, Quick SelectJava
• Shuffling : usingFisher–Yates shuffle algorithm    Java
• GaussElimination : Gauss elimination or Gauss Jordan method to solve system of linear equationsJava
• Point2D : Data structure to represent point in 2D spaceJava
• Point3D : Data structure to represent point in 3D spaceJava
• Generate Nth row of Pascal triangle
  • RecursiveC++
  • IterativeC++
• Happy numberWikiC++
• Excel Sheet Column NumberC++
• Number of zeros in facorialC++
• Implement power functionC++
• Implement square root functionC++

• Permutation of objectsJava
• Unique pathsC++

• Print all possible decoding of given digit sequence.C++
• Print all possible decoding of given digit sequence.C++

• Find the celebrity in room.C++
• Maximum possible length by cutting N wood pieces into K pieces.C++
• Merge N trasactions preserve order.C++
• Stock Buy Sell to Maximize Profit.C++
• Find majority element.Problem
  • Brute ForceC++
  • using hashmapC++
  • Boyer-Moore voting algorithmwiki articleC++
• CPU task schedulingC++
• Activity/Task : representation of an activity or a taskJava
• Randomized setProblemC++
• Disjoint set
  • Naive implementationC++
  • Path compression, union by rankC++

• BasicsJava
• QuestionsLinks 1
• Bit Twiddling Hackscollection

• Closest pair of points : Divide and conquer algorithmJava
• Collinear pointsJava
• Group points which are at distance less than k : brute force algorithmJava
• Group points which are at distance less than k : divide and conquer algorithmJava

• Random String : generate random stringJava
• Random 2D Matrix : generate random 2D boolean, binary or integer matrixJava

• Running sum  Problem
  • using loop, using partial sum, using accumulateC++

• Top K frequent elements    Problem
  • Using hashmap and sortingC++
  • Using hashmap and priority queueC++
  • Using Quick SelectC++

• Reverse String    Problem
  • Java
  • C++
• Reverse Integer    Problem
  • C++
• First unique character in a string    Problem
  • C++
• Valid anagram    Problem
  • C++
• Valid palindrome    Problem
  • C++
• Longest Common Prefix    Problem
  • Brute Force 1C++
  • Brute Force 2C++
  • Using TrieC++

• Delete Node (without previous)    Problem
  • Simple DeleteC++
• Remove Nth from end    Problem
  • Simple DeleteC++
• Reverse a linked list    Problem
  • IterativeC++
  • RecursiveC++
• Merge two sorted    Problem
  • SimpleC++
• Palindrome List    Problem
  • Double ReverseC++
• Cycle in Linked List    Problem
  • Slow and fast pointerC++
• Sum two numbers    Problem
  • C++
• Odd Even Linked List    Problem
  • C++
• Intersection of Two Linked Lists    Problem
  • Difference of LengthsC++
  • Traversal Pointer reassignmentC++

• Max depth    Problem
  • Max DepthC++
• Validate Binary search Tree    Problem
  • Validate BSTC++
• Symmeric Binary Tree    Problem
  • IterativeC++
  • RecursiveC++
• Level Order Of Tree    Problem
  • Using queueC++
• Sorted Array to Binary Search Tree    Problem
  • RecursiveC++
• Inorder traversal    Problem
  • Iterative using stackC++
  • RecursiveC++
• Zigzag/spiral level order traversal    Problem
  • C++
• Construct Binary Tree from Preorder and Inorder Traversal    Problem
  • C++
• Populating Next Right Pointers in Each NodeProblem
  • Iterative level orderC++
  • Using queueC++
• Kth Smallest Element in a BST    Problem
  • Iterative using stackC++
  • RecursiveC++
• Kth Largest Element in a BST | ?? | ? |
  • Iterative using stackC++
  • RecursiveC++
• Number of Islands    Problem
  • Using DFSC++
  • Using BFSC++
  • Using disjoint setC++

• Letter Combinations of a Phone Number    Problem
  • IterativeC++
  • RecursiveC++
• Generate Balanced Parentheses    Problem
  • RecursiveC++

• Permutations    Problem
  • BacktrackingC++
• Subset    Problem
  • BacktrackingC++
• Subset without duplicates    Problem
  • BacktrackingC++
• Combination Sum    Problem
  • BacktrackingC++
• Combination Sum without duplicates    Problem
  • BacktrackingC++
• Word Search |Link
  • Not working, Recursive DFSC++