Coding challenges

In this repository, I store my solutioins to the common programming problems. Currently, I try to implement each solution in Python and Java, maybe sometimes C++. By doing so, I can compare languages with respect to implementations.

The solutions in this repo are not meant to be the best ones. You may find better solutions out there. What is more, you can come up with your own solution which can be considered as the best one. Bear in mind that in practice optimal solution depends on various parameters such as workset data, environment, constraints etc.

Challenge	Description	Python	Java	C++
Determine if a string contains unique characters	Challenge	Solution	Solution	-
Determine if a string is a permutation of another	Challenge	Solution	Solution	-
Determine if a string is a rotation of another	Challenge	-	Solution	-
Compress a string	Challenge	Solution	Solution	-
Reverse strings in a string	Challenge	Solution	Solution	-
Find the first non-repeated character in a string	-	Solution	Solution	-

Linked Lists

Challenge	Description	Python	Java	C++
Implement a sorted linked list	-	-	-	Solution
Remove duplicates from a linked list	Challenge	-	-	Solution
Find the kth to last element of a linked list	Challenge	-	-	Solution
Delete a node in the middle of a linked list	Challenge	-	-	-
Partition a linked list around a given value	Challenge	-	-	-
Add two numbers whose digits are stored in a linked list	Challenge	-	-	-
Find the start of a linked list loop	Challenge	-	-	-
Determine if a linked list is a palindrome	Challenge	-	-	-
Implement a linked list	Challenge	-	-	-
Determine if a list is cyclic or acyclic	Contribute	-	-	-

Stacks and Queues

Challenge	Description	Python	Java	C++
Implement a stack using a linked list	-	-	Solution	-
Implement a stack using a fixed array	-	-	Solution	-
Implement a stack using a resizable array	-	-	Solution	-
Implement a queue using a linked list	-	-	Solution	-
Implement a queue using a fixed array	-	-	Solution	-
Implement a queue using a resizable array	-	-	Solution	-

Sorting

Challenge	Description	Python	Java	C++
Implement an insertion sorting .	-	-	Solution	-
Implement a selection sorting .	-	-	Solution	-
Implement a shell sorting .	-	-	Solution	-

Trees and Graphs

Challenge	Description	Python	Java	C++
Given an array A of integers, find any 3 of them that sum to 0.	Definition	-	Solution	-
Implement Union-Find algorithm	Definition	-	Solution	-

Graphs and Trees

Challenge	Description	Python	Java	C++
Implement depth-first search (pre-, in-, post-order) on a tree	Challenge	-	Solution	-
Implement breadth-first search on a tree	Challenge	-	Solution	-
Determine the height of a tree	Challenge	-	-	-
Create a binary search tree with minimal height from a sorted array	Challenge	-	-	-
Find diameter length and nodes of a binary tree	-	-	Solution	-
Create a linked list for each level of a binary tree	Challenge	-	-	-
Check if a binary tree is balanced	Challenge	-	-	-
Determine if a tree is a valid binary search tree	Challenge	-	-	-
Find the in-order successor of a given node in a binary search tree.	Challenge	-	-	-
Implement a binary search tree	Challenge	-	-	-
Implement depth-first search on a graph	Challenge	-	-	-
Implement breadth-first search on a graph	Challenge	-	-	-
Determine if there is a path between two nodes in a graph	Challenge	-	-	-
Implement a graph	Challenge	-	-	-
Print a tree using pre-order traversal without recursion	Contribute	-	-	-
Determine the lowest common ancestor of two nodes	Contribute	-	-	-
Transform a binary tree into a heap	Contribute	-	-	-
Implement a right and left rotation on a tree	Contribute	-	-	-
Check if a binary tree is binary search tree	Contribute	-	-	-
Add a challenge	Contribute	-	-	-

10 Days of Statistics

https://www.hackerrank.com/domains/tutorials/10-days-of-statistics

Challenge	Description	Python	Java	C++
Day 4: Binomial Distribution I	Definition	Solution	-	-
Day 4: Binomial Distribution II	Definition	Solution	-	-
Day 4: Geometric Distribution I	Definition	Solution	-	-
Day 5: Poisson Distribution I	Definition	Solution	-	-
Day 5: Poisson Distribution II	Definition	Solution	-	-
Day 5: Normal Distribution I	Definition	Solution	-	-
Day 5: Normal Distribution II	Definition	Solution	-	-

Hackerrank Random

https://www.hackerrank.com/challenges/

Challenge	Description	Python	Java	C++
Designer PDF Viewer	Definition	Solution	Solution	-

https://github.com/donnemartin/interactive-coding-challenges

Code reviews and comments, even new challenges are very welcomed :)