Disclaimer

	Most of the problems are solved by using the Algo library.
	Solutions to HackerRank problems.
	Solutions to LeetCode problems.

The problem solutions and implementations are entirely provided by Alex Prut. The code is not refactored, no coding style is followed, the only purpose of the written code is to pass all the platform tests of a given problem.

Table of contents

1. Time Complexity
2. Arrays
3. Math
4. Binary Search
5. Strings
6. Bit Manipulation
7. Two Pointers
8. Linked Lists
9. Stacks And Queues
10. Backtracking
11. Hashing
12. Heaps And Maps
13. Tree Data Structure
14. Dynamic Programming
15. Greedy Algorithm
16. Graph Data Structure And Algorithms

Time Complexity

Subdomain	Challenge	Score	Solution
Basic primer	LOOP_CMPL	20	Solution.txt
Basic primer	NESTED_CMPL	20	Solution.txt
Basic primer	NESTED_CMPL2	30	Solution.txt
Basic primer	CHOOSE4	50	Solution.txt
Math	WHILE_CMPL	50	Solution.txt
Math	NESTED_CMPL3	80	Solution.txt
Math	LOOP_CMPL2	80	Solution.txt
Math	GCD_CMPL	150	Solution.txt
Compare functions	CHOOSE1	50	Solution.txt
Compare functions	CHOOSE3	50	Solution.txt
Compare functions	CHOOSE2	80	Solution.txt
Function calling itself	REC_CMPL1	80	Solution.txt
Function calling itself	REC_CMPL2	80	Solution.txt
Function calling itself	REC_CMPL3	150	Solution.txt
Amortized complexity	AMORTIZED1	100	Solution.txt

Arrays

Subdomain	Challenge	Score	Solution
Array math	Min Steps in Infinite Grid	150	Solution.java
Array math	Add One To Number	225	Solution
Array math	Max Sum Contiguous Subarray	225	Solution
Array math	Maximum Absolute Difference	250	Solution
Array math	Repeat and Missing Number Array	350	Solution
Array math	Flip	400	Solution
Simulation array	Max Non Negative SubArray	150	Solution.java
Simulation array	Spiral Order Matrix II	225	Solution
Simulation array	Pascal Triangle	225	Solution.java
Simulation array	Kth Row of Pascal's Triangle	225	Solution
Simulation array	Anti Diagonals	225	Solution
Bucketing	Noble Integer	200	Solution.java
Bucketing	Triplets with Sum between given range	200	Solution
Bucketing	Largest Number	225	Solution.java
Bucketing	Wave Array	225	Solution.java
Bucketing	Hotel Bookings Possible	225	Solution
Bucketing	Max Distance	250	Solution
Bucketing	Maximum Unsorted Subarray	250	Solution
Bucketing	Find Duplicate in Array	450	Solution.java
Bucketing	Maximum Consecutive Gap	450	Solution
Array	MAXSPPROD	200	Solution.java
Arrangement	Largest Number	225	Solution.java
Arrangement	Rotate Matrix	300	Solution
Arrangement	Next Permutation	300	Solution
Arrangement	Find Permutation	300	Solution
Value ranges	Merge Intervals	225	Solution
Value ranges	Merge Overlapping Intervals	225	Solution.java
Bucketing or sorting	Hotel Bookings Possible	225	Solution
Bucketing or sorting	Wave Array	225	Solution.java
Bucketing or sorting	Largest Number	225	Solution.java
Bucketing or sorting	Max Distance	250	Solution
Bucketing or sorting	Maximum Unsorted Subarray	250	Solution
Bucketing or sorting	Find Duplicate in Array	450	Solution.java
Bucketing or sorting	Maximum Consecutive Gap	450	Solution
Space recycle	Set Matrix Zeros	300	Solution.java
Space recycle	First Missing Integer	300	Solution
Missing / repeated number	First Missing Integer	300	Solution
Missing / repeated number	Repeat and Missing Number Array	350	Solution
Missing / repeated number	Find Duplicate in Array	450	Solution.java
Missing / repeated number	N/3 Repeat Number	600	Solution

Math

Subdomain	Challenge	Score	Solution
Adhoc	Prime Sum	150	Solution.java
Adhoc	Sum of pairwise Hamming Distance	200	Solution
Adhoc	FizzBuzz	200	Solution.java
Adhoc	Power Of Two Integers	250	Solution
Base conversion	Excel Column Number	175	Solution.java
Base conversion	Excel Column Title	175	Solution
Digit op	Palindrome Integer	200	Solution.java
Digit op	Reverse integer	200	Solution
Number theory	Greatest Common Divisor	200	Solution.java
Number theory	Trailing Zeros in Factorial	250	Solution
Number theory	Sorted Permutation Rank	250	Solution
Number theory	Largest Coprime Divisor	250	Solution
Number theory	Sorted Permutation Rank with Repeats	500	Solution
Array dp	Numbers of length N and value less than K	200	Solution
Number encoding	Rearrange Array	250	Solution.java
Combinatorics	City Tour	300	Solution
Combinatorics	Grid Unique Paths	375	Solution.java

Binary Search

Subdomain	Challenge	Score	Solution
Search answer	Matrix Median	225	Solution
Search answer	Square Root of Integer	275	Solution.java
Search answer	Painter's Partition Problem	350	Solution
Search answer	Allocate Books	350	Solution
Simple binary search	Matrix Search	250	Solution.java
Simple binary search	Search for a Range	250	Solution.java
Simple binary search	Sorted Insert Position	250	Solution.java
Search step simulation	Implement Power Function	275	Solution
Sort modification	Rotated Sorted Array Search	325	Solution.java
Sort modification	Median of Array	325	Solution

Strings

Subdomain	Challenge	Score	Solution
String simulation	Palindrome String	150	Solution.java
String simulation	Longest Common Prefix	225	Solution
String simulation	Count And Say	250	Solution
Programming	Amazing Subarrays	150	Solution.java
Programming	Stringoholics	300	Solution
String tricks	Minimum Characters required to make a String Palindromic	200	Solution
String tricks	Longest Palindromic Substring	500	Solution
String search	Minimum Characters required to make a String Palindromic	200	Solution
String search	Implement StrStr	225	Solution.java
String parsing	Minimum Characters required to make a String Palindromic	200	Solution
String parsing	Compare Version Numbers	225	Solution
String parsing	Atoi	250	Solution
String parsing	Valid Number	250	Solution
String parsing	Valid Ip Addresses	250	Solution
Words	Length of Last Word	225	Solution.java
Words	Reverse the String	250	Solution
String math	Roman To Integer	250	Solution.java
String math	Integer To Roman	250	Solution
String math	Add Binary Strings	300	Solution
String math	Power of 2	350	Solution
String math	Multiply Strings	375	Solution
Pretty print	Justified Text	300	Solution
Pretty print	Zigzag String	300	Solution.java
Pretty print	Pretty Json	400	Solution

Bit Manipulation

Subdomain	Challenge	Score	Solution
Bucketing	Min XOR value	200	Solution.java
Bit play	Number of 1 Bits	200	Solution.java
Bit play	Reverse Bits	225	Solution.java
Bit play	Divide Integers	250	Solution
Bit play	Different Bits Sum Pairwise	300	Solution
Bit array	Single Number	275	Solution.java
Bit array	Single Number II	275	Solution

Two Pointers

Subdomain	Challenge	Score	Solution
Multiple arrays	Merge Two Sorted Lists II	200	Solution.java
Multiple arrays	Intersection Of Sorted Arrays	225	Solution.java
Two pointer	Minimize the absolute difference	200	Solution
Sorting	3 Sum	225	Solution
Sorting	3 Sum Zero	225	Solution
Sorting	Counting Triangles	225	Solution
Sorting	Diffk	300	Solution.java
Inplace update	Remove Duplicates from Sorted Array	250	Solution.java
Inplace update	Remove Duplicates from Sorted Array II	250	Solution
Inplace update	Remove Element from Array	250	Solution
Inplace update	Sort by Color	325	Solution.java
Tricks	Max Continuous Series of 1s	300	Solution
Tricks	Array 3 Pointers	400	Solution
Tricks	Container With Most Water	400	Solution.java

Linked Lists

Subdomain	Challenge	Score	Solution
List 2 pointer	Palindrome List	200	Solution
List 2 pointer	Remove Duplicates from Sorted List	300	Solution.java
List 2 pointer	Remove Duplicates from Sorted List II	300	Solution
List 2 pointer	Merge Two Sorted Lists	300	Solution.java
List 2 pointer	Remove Nth Node from List End	350	Solution
List 2 pointer	Rotate List	350	Solution.java
List 2 pointer	Reverse Link List II	450	Solution
List 2 pointer	Reorder List	600	Solution
Pointer move	K reverse linked list	200	Solution
Pointer move	Swap List Nodes in pairs	350	Solution.java
Pointer move	Reverse Link List II	450	Solution
Pointer move	Reorder List	600	Solution
List math	Add Two Numbers as Lists	250	Solution
List math	List Cycle	600	Solution.java
List sort	Partition List	275	Solution
List sort	Insertion Sort List	300	Solution.java
List sort	Sort List	350	Solution
List trick	Reverse Link List II	450	Solution
List trick	Reorder List	600	Solution
List cycle	List Cycle	600	Solution.java

Stacks And Queues

Subdomain	Challenge	Score	Solution
Stack simple	Simplify Directory Path	250	Solution
Stack simple	Redundant Braces	300	Solution.java
Cleverstack	Nearest Smaller Element	350	Solution.java
Cleverstack	Largest Rectangle in Histogram	450	Solution
Cleverstack	Sliding Window Maximum	450	Solution
Stack math	Evaluate Expression	400	Solution.java
Stack math	Rain Water Trapped	400	Solution
Multiple stack	Min Stack	400	Solution

Backtracking

Subdomain	Challenge	Score	Solution
Subsets	Subset	250	Solution.java
Subsets	Combinations	300	Solution
Subsets	Combination Sum	300	Solution
Subsets	Combination Sum II	300	Solution
Subsets	Subsets II	300	Solution
Bruteforce builder	Letter Phone	250	Solution
Bruteforce builder	Palindrome Partitioning	300	Solution
Bruteforce builder	Generate all Parentheses II	350	Solution.java
Pruned builder	Palindrome Partitioning	300	Solution
Bruteforce builder	Generate all Parentheses II	350	Solution.java
Pruned builder	NQueens	550	Solution
Pruned builder	Sudoku	700	Solution
Permutations	Permutations	350	Solution.java
Maths and backtracking	Gray Code	350	Solution
Maths and backtracking	Kth Permutation Sequence	350	Solution
Game solving	NQueens	550	Solution
Game solving	Sudoku	700	Solution

Hashing

Subdomain	Challenge	Score	Solution
Hash search	Colorful Number	150	Solution
Hash search	Largest Continuous Sequence Zero Sum	200	Solution
Hash search	2 Sum	300	Solution
Hash search	4 Sum	325	Solution
Hash search	Valid Sudoku	325	Solution
Hash search	Diffk II	375	Solution.java
Key formation	Anagrams	350	Solution.java
Key formation	Equal	350	Solution
Key formation	Copy List	450	Solution
Hashing two pointer	Longest Substring Without Repeat	350	Solution.java
Hashing two pointer	Window String	350	Solution
Maths and hashing	Fraction	450	Solution
Maths and hashing	Points on the Straight Line	450	Solution
Incremental hash	Substring Concatenation	1000	Solution

Heaps And Maps

Subdomain	Challenge	Score	Solution
Heap	N max pair combinations	200	Solution
Heap	Magician and Chocolates	250	Solution.java
Heap	Merge K Sorted Lists	600	Solution.java
Math	Ways to form Max Heap	200	Solution
Heapmap	Distinct Numbers in Window	600	Solution.java
Heapmap	LRU Cache	1000	Solution

Tree Data Structure

Subdomain	Challenge	Score	Solution
Traversal	Vertical Order traversal of Binary Tree	200	Solution
Traversal	Inorder Traversal	350	Solution
Traversal	Postorder Traversal	350	Solution
Traversal	Preorder Traversal	350	Solution.java
Tries	Hotel Reviews	200	Solution
Simple tree ops	Balanced Binary Tree	275	Solution.java
2 trees	Identical Binary Trees	300	Solution.java
2 trees	Symmetric Binary Tree	300	Solution
Tree construction	Inorder Traversal of Cartesian Tree	300	Solution
Tree construction	Sorted Array To Balanced BST	300	Solution.java
Tree construction	Binary Tree From Inorder And Postorder	375	Solution
Tree construction	Construct Binary Tree From Inorder And Preorder	375	Solution
Bst traversal	Kth Smallest Element In Tree	300	Solution.java
Bst traversal	2-Sum Binary Tree	400	Solution
Bst traversal	BST Iterator	500	Solution
Bst traversal	Recover Binary Search Tree	750	Solution
Inplace change	Invert the Binary Tree	300	Solution.java
Level order	ZigZag Level Order Traversal BT	350	Solution.java
Level order	Populate Next Right Pointers Tree	900	Solution
Root to leaf	Path Sum	350	Solution
Root to leaf	Root to Leaf Paths With Sum	350	Solution
Root to leaf	Max Depth of Binary Tree	350	Solution.java
Root to leaf	Min Depth of Binary Tree	350	Solution
Root to leaf	Sum Root to Leaf Numbers	350	Solution
Trie	Shortest Unique Prefix	350	Solution
Tree search	Least Common Ancestor	450	Solution.java
Linkedlist tree	Flatten Binary Tree to Linked List	500	Solution.java
Interval tree	Order of People Heights	700	Solution

Dynamic Programming

Subdomain	Challenge	Score	Solution
Simple array dp	Length of Longest Subsequence	200	Solution.java
Simple array dp	Largest area of rectangle with permutations	200	Solution
Simple array dp	Ways to Decode	225	Solution
Simple array dp	Stairs	225	Solution.java
Simple array dp	Intersecting Chords in a Circle	300	Solution
Greedy or dp	Tushar's Birthday Bombs	200	Solution
Greedy or dp	Jump Game Array	225	Solution.java
Greedy or dp	Min Jumps Array	300	Solution
Dp tricky	Longest Arithmetic Progression	200	Solution
Dp tricky	N digit numbers with digit sum S	200	Solution
Dp tricky	Ways to color a 3xN Board	200	Solution
Dp tricky	Shortest common superstring	200	Solution
Dp tricky	Kth Manhattan Distance Neighbourhood	200	Solution
Dp tricky	Coins in a Line	300	Solution
Dp tricky	Evaluate Expression To True	350	Solution
Dp tricky	Longest valid Parentheses	700	Solution
Dp tricky	Best Time to Buy and Sell Stocks III	700	Solution
Matrix dp	Kingdom War	200	Solution
Matrix dp	Min Sum Path in Matrix	300	Solution.java
Matrix dp	Dungeon Princess	300	Solution
Matrix dp	Min Sum Path in Triangle	300	Solution
Matrix dp	Unique Paths in a Grid	300	Solution.java
Matrix dp	Max Rectangle in Binary Matrix	350	Solution
Matrix dp	Rod Cutting	350	Solution
Matrix dp	Queen Attack	350	Solution
Suffix / prefix dp	Sub Matrices with sum Zero	200	Solution
Suffix / prefix dp	Coin Sum Infinite	225	Solution
Suffix / prefix dp	Best Time to Buy and Sell Stocks I	300	Solution.java
Suffix / prefix dp	Max Product Subarray	300	Solution
Suffix / prefix dp	Arrange II	350	Solution
Adhoc	Largest area of rectangle with permutations	200	Solution
Adhoc	Best Time to Buy and Sell Stocks II	225	Solution.java
Knapsack	N digit numbers with digit sum S	200	Solution
Knapsack	Tushar's Birthday Party	200	Solution
Knapsack	Flip Array	200	Solution
Knapsack	Equal Average Partition	350	Solution
Derived dp	Max Sum Without Adjacent Elements	225	Solution
2d string dp	Edit Distance	300	Solution.java
2d string dp	Longest Increasing Subsequence	300	Solution.java
2d string dp	Repeating Sub-Sequence	300	Solution.java
2d string dp	Distinct Subsequences	325	Solution
2d string dp	Interleaving Strings	500	Solution
2d string dp	Regular Expression Match	500	Solution
2d string dp	Regular Expression II	500	Solution
2d string dp	Scramble String	500	Solution
Multiply dp	Intersecting Chords in a Circle	300	Solution
Multiply dp	Unique Binary Search Trees II	400	Solution
Multiply dp	Count Permutations of BST	400	Solution
Preprocess dp	Max Rectangle in Binary Matrix	350	Solution
Dp optimized backtrack	Word Break II	350	Solution
Tree dp	Max Sum Path in Binary Tree	400	Solution
Breaking words	Word Break	400	Solution
Breaking words	Palindrome Partitioning II	400	Solution
Breaking words	Scramble String	500	Solution

Greedy Algorithm

Subdomain	Challenge	Score	Solution
Bucket 5	Highest Product	200	Solution.java
Bucket 6	Bulbs	200	Solution.java
Bucket 1	Distribute Candy	300	Solution
Bucket 1	Assign Mice to Holes	300	Solution.java
Bucket 4	Seats	300	Solution
Bucket 3	Majority Element	400	Solution.java
Bucket 2	Gas Station	700	Solution

Graph Data Structure And Algorithms

Subdomain	Challenge	Score	Solution
Bfs	Smallest sequence with given Primes	200	Solution.java
Bfs	Valid Path	200	Solution
Bfs	Level Order	300	Solution.java
Bfs	Smallest Multiple With 0 and 1	300	Solution
Graph connectivity	Commutable Islands	200	Solution
Graph connectivity	Possibility of finishing all courses given pre-requisites	200	Solution
Graph connectivity	Valid Path	200	Solution
Graph connectivity	Black Shapes	300	Solution.java
Graph connectivity	Capture Regions on Board	500	Solution
Depth first search	Largest Distance between nodes of a Tree	200	Solution
Graph traversal	Level Order	300	Solution.java
Graph traversal	Stepping Numbers	300	Solution
Graph traversal	Capture Regions on Board	500	Solution
Graph traversal	Word Search Board	500	Solution
Graph adhoc	Convert Sorted List to Binary Search Tree	300	Solution.java
Shortest path	Sum Of Fibonacci Numbers	300	Solution.java
Shortest path	Knight On Chess Board	300	Solution
Shortest path	Word Ladder I	600	Solution
Shortest path	Word Ladder II	800	Solution
Graph hashing	Clone Graph	500	Solution

License

Licensed under MIT.