acneuromancer / ds_algo

Data structures & Algorithms implementation in Python/Java.

Data structures & Algorithms (Python/Java)

Index

• Topics
  • Tree
  • Graph
  • Array
  • Dynamic programming
  • Searching
  • Sorting
  • Backtracking
  • Heap
  • Trie
  • Queue
  • Linked list
  • Misc
• How to run?

Topics

Tree

• BST - CRUD, min-max, height etc.
• Serialization & Deserialization - Binary Tree
• Serialization & Deserialization - Binary Search Tree
• Check if tree is BST
• Path(s) from root to leaves
• Convert a unbalanced BST to balanced BST
• Construct a BST from given sorted array
• Children sum property - For each node, node.data = node.left.data + node.right.data (for leaves data=0)
• Distance between 2 arbitrary nodes
• Distance between root & any arbitrary node
• Inorder successor & predecessor
• To check whether binary is balanced
• Path with sum equals to given sum
• Pair(s) with sum equals to given sum
• Tree views - Top, Left, Bottom, Right
• LCA - Lowest Common Ancestor
• To check whether binary trees are mirror of each other
• Convert a binary tree to it's mirror
• Move children to left/right
• To find node(s) at distance 'k' from root
• To find path from root to a given node
• To find out sum of all nodes' data
• Binary tree traversals - Preorder, Inorder, Postorder, Level order, Spiral(zig-zag)
• Vertical sum of binary tree
• Diameter of binary tree
• Maximum width of binary tree
• Height of binary tree
• Print diagonals of binary tree
• Diagonal sum of a binary tree
• Binary tree to DDL
• Isomorphic trees
• Segment Tree
  • Min-Range
  • Sum-Range

Graph

• Representation - Sparse matrix, Adjecency list
• Traversals - BFS, DFS
• Topological sort - Using DFS, Kahn's algo
• Detect cycle - Directed graph(Using DFS coloring, topological order)
• Detect cycle - Undirected graph(Using disjoint set, BFS, DFS, DFS coloring)
• Disjoint set
• Minimum spanning tree - Prim's algorithm
• Minimum spanning tree - Kruskal's algorithm
• Single source shortest path - Dijkstra's algorithm
• Single source shortest path - Bellman-Ford's algorithm
• All pairs shortest path - Floyd-Warshall's algorithm
• Knight tour with custom rules - Warnsdorff's algorithm

Array

• To reverse an array
• To rotate an array by 'd'
• To find out Pair(s) with given sum 's' in sorted array
• To find out Pair(s) with given sum 's' in unsorted array
• Rearrange numbers in array such that +ve & -ve numbers are placed alternatively
• Move all -ve numbers to the left and +ve numbers to the right in array
• Segregate 0's & 1's in an array
• Segregate 0's, 1's & 2's in an array (Dutch-National-Flag algorithm)
• Rearrange an array in max-min form, i.e. 1st max, 1st min, 2nd max, 2nd min
• The longest sub-array having equal numbers of 0s and 1s
• Maximum product sub-array & minimum product sub-array
• Form largest number by re-arranging array elements
• Kadane's algorithm, max sum sub-array
• Find element in row-wise & col-wise sorted matrix
• Given prices in increasing order of time, buy, sell & maximize profit
• Find zeroes to be flipped so that number of consecutive 1’s is maximized
• Predecessor in sorted array
• Next greater elements
• Next greatest elements
• Checks if number is prime
• Fibonacci Series
• Factorial of a number
• Leader(s) in array
• Majority element - Moore's voting algorithm
• Minimum from Stack in constant O(1) time
• Minimum steps to reach a target
• Stock-Span problem
• Median of two sorted arrays

Dynamic programming

• To find out the number of BSTs can be formed with 'n' sorted elements/keys
• Check if array can be partitioned into two subsets such that the sum of elements in both subsets is same
• Coin change problem
• Knapsack 0-1 problem
• Longest common sub-sequence(LCS)
• Longest repeated sub-sequence(LRS)
• Longest increasing sub-sequence(LIS)
• Subset-sum problem
• Cutting rod into pieces to maximize profit
• Square sub-matrix with maximum consecutive 1's
• Minimum jump(s) required to reach at the end of the array
• Number of ways to reach some position in matrix(moves: right, bottom)
• Ugly numbers
• Super-Ugly numbers
• Weighted-job-scheduling
• Minimum Number of Platforms Required for a Railway/Bus Station

Backtracking

• All combinations of input sequence
• All permutations of input sequence
• N-Queens problem

Searching

• Binary search
• Binary search in circularly sorted array
• To find out the number of times sorted array is rotated

Sorting

• Bubble sort
• Insertion sort
• Selection sort
• Merge sort
• Quick sort

Heap

• Min-Heap
• Max-Heap

Trie

• Trie - Insert, Search, Prefix-Search(autocomplete), Delete
• Contacts list - Add, search, prefix search, count, delete

Queue

• Queue
• Dequeue
• Priority Queue
• Implement queue using stack(s)

Linked list

• Singly linked list - Insert at first, last and in middle
• Deleting a node from singly linked list
• Merge two sorted linked lists
• Doubly linked list - Insertion, deletion
• Add 2 numbers represented by linked lists and save to new linked list
• Multiply 2 numbers represented by linked lists

Misc

• LRU Cache
• Custom hashtable implementation
• Custom thread pool
• Time-based Cache with TTL(Like Redis/Aerospike)
• Villagers-Queue-Bucket problem
• Battleship game
• Check if strings are anagrams

How to run?

For python files:

1. Move to <project-dir>, create virtual environment and then activate it as

$ cd <project-dir>
$ virtualenv -p python3 .environment
$ source .environment/bin/activate

Note: Step-1 is optional but recommended.

2. Add project to PYTHONPATH as

$ export PYTHONPATH="$PYTHONPATH:." # . corresponds to current directory(project-dir)

If you are using PyCharm then it can be done under run configuration.

For java files:

1. Compile & Run

javac <file_name>.java
java <Main>