(Highly Efficient:zap:) solutions to problems on HackerRank implemented with Python.

| hackerrank | algorithms| data structures | mathematics | c | c++ | java | python | ruby | linux shell | functional programming | artificial intelligence | sql | databases | regex | interview preparation kit |30 days of code| 10 days of statistics |10 days of javascript |

Algorithms

#	Problem	Solution	Difficulty	Max Score	Sub domain
1	Solve Me First	Solution	Easy	1	Warmup
2	Simple Array Sum	Solution	Easy	10	Warmup
3	Compare the Triplets	Solution	Easy	10	Warmup
4	A Very Big Sum	Solution	Easy	10	Warmup
5	Diagonal Difference	Solution	Easy	10	Warmup
6	Plus Minus	Solution	Easy	10	Warmup
7	Staircase	Solution	Easy	10	Warmup
8	Mini-Max Sum	Solution	Easy	10	Warmup
9	Birthday Cake Candles	Solution	Easy	10	Warmup
10	Time Conversion	Solution	Easy	15	Warmup
11	Grading Students	Solution	Easy	10	Implementation
12	Apple and Orange	Solution	Easy	10	Implementation
13	Kangaroo	Solution	Easy	10	Implementation
14	Breaking the Records	Solution	Easy	10	Implementation
15	Forming a Magic Square	Solution	Medium	20	Implementation
16	Find Digits	Solution	Easy	25	Implementation
17	Extra Long Factorials	Solution	Medium	20	Implementation
18	Append and Delete	Solution	Easy	20	Implementation
19	Sherlock and Squares	Solution	Easy	20	Implementation
20	Matrix Layer Rotation	Solution	Hard	80	Implementation
21	Super Reduced String	Solution	Easy	10	Implementation
22	Sherlock and The Beast	Solution	Easy	30	Greedy
23	Max Min	Solution	Medium	35	Greedy
24	Goodland Electricity	Solution	Medium	40	Greedy
25	Lonely Integer	Solution	Easy	20	Bit Manipulation
26	The Coin Change Problem	Solution	Medium	60	Dynamic Programming
27	Equal	Solution	Medium	30	Dynamic Programming
28	Greedy Florist	Solution	Medium	35	Greedy
29	Sherlock and Cost	Solution	Medium	50	Dynamic Programming
30	Jim and the Orders	Solution	Easy	40	Greedy
31	Permuting Two Arrays	Solution	Easy	40	Greedy
32	Construct the Array	Solution	Medium	35	Dynamic Programming
33	Minimum Absolute Difference in an Array	Solution	Easy	15	Greedy
34	Marc's Cakewalk	Solution	Easy	15	Greedy
35	Grid Challenge	Solution	Easy	20	Greedy
36	Luck Balance	Solution	Easy	20	Greedy
37	Maximum Perimeter Triangle	Solution	Easy	20	Greedy
38	Candies	Solution	Medium	50	Greedy
39	Beautiful Pairs	Solution	Easy	30	Greedy
40	Sam and substrings	Solution	Medium	40	Dynamic Programming
41	Priyanka and Toys	Solution	Easy	30	Greedy
42	Fibonacci Modified	Solution	Medium	45	Dynamic Programming
43	Largest Permutation	Solution	Easy	30	Greedy
44	Mark and Toys	Solution	Easy	35	Greedy
45	Abbreviation	Solution	Medium	40	Dynamic Programming
46	Chief Hopper	Solution	Hard	65	Greedy
47	Between Two Sets	Solution	Easy	10	Implementation
48	Sub-array Division	Solution	Easy	10	Implementation
49	Divisible Sum Pairs	Solution	Easy	10	Implementation
50	Migratory Birds	Solution	Easy	10	Implementation
51	Day of the Programmer	Solution	Easy	15	Implementation
52	Bill Division	Solution	Easy	10	Implementation
53	Drawing Book	Solution	Easy	10	Implementation
54	Electronics Shop	Solution	Easy	15	Implementation
55	Cats and a Mouse	Solution	Easy	15	Implementation
56	Picking Numbers	Solution	Easy	20	Implementation
57	Climbing the Leaderboard	Solution	Medium	20	Implementation
58	The Hurdle Race	Solution	Easy	15	Implementation
59	Designer PDF Viewer	Solution	Easy	20	Implementation
60	Utopian Tree	Solution	Easy	20	Implementation
61	Angry Professor	Solution	Easy	20	Implementation
62	Beautiful Days at the Movies	Solution	Easy	15	Implementation
63	Viral Advertising	Solution	Easy	15	Implementation
64	Save the Prisoner!	Solution	Easy	15	Implementation
65	Circular Array Rotation	Solution	Easy	20	Implementation
66	Sequence Equation	Solution	Easy	20	Implementation
67	Jumping on the Clouds: Revisited	Solution	Easy	15	Implementation
68	Library Fine	Solution	Easy	15	Implementation
69	Cut the sticks	Solution	Easy	25	Implementation
70	Non-Divisible Subset	Solution	Medium	20	Implementation
71	Equalize the Array	Solution	Easy	20	Implementation
72	Queen's Attack II	Solution	Medium	30	Implementation
73	ACM ICPC Team	Solution	Easy	25	Implementation
74	Taum and B'day	Solution	Easy	25	Implementation

Data Structures

#	Problem	Solution	Difficulty	Max Score	Sub domain
1	Array - DS	Solution	Easy	10	Arrays
2	2D Array - DS	Solution	Easy	15	Arrays
3	Dynamic Array	Solution	Easy	15	Arrays
4	Left Rotation	Solution	Easy	20	Arrays
5	Sparse Arrays	Solution	Medium	25	Arrays
6	Array Manipulation	Solution	Hard	60	Arrays
7	Delete duplicate-value nodes from a sorted linked list	Solution	Easy	5	Linked Lists
8	Cycle Detection	Solution	Medium	5	Linked Lists
9	Find Merge Point of Two Lists	Solution	Easy	5	Linked Lists
10	Inserting a Node Into a Sorted Doubly Linked List	Solution	Easy	5	Linked Lists
11	Reverse a doubly linked list	Solution	Easy	5	Linked Lists
12	QHEAP1	Solution	Easy	25	Heap
13	Jesse and Cookies	Solution	Easy	25	Heap
14	Find the Running Median	Solution	Hard	50	Heap
15	Equal Stacks	Solution	Easy	25	Stacks
16	Minimum Average Waiting Time	Solution	Hard	80	Heap
17	Game of Two Stacks	Solution	Medium	30	Stacks
18	Balanced Brackets	Solution	Medium	25	Stacks
19	Largest Rectangle	Solution	Medium	50	Stacks
20	Simple Text Editor	Solution	Medium	65	Stacks
21	Poisonous Plants	Solution	Hard	70	Stacks
22	AND xor OR	Solution	Hard	70	Stacks
23	Waiter	Solution	Medium	75	Stacks
24	Maximum Element	Solution	Easy	20	Stacks
25	Insert a node at the head of a linked list	Solution	Easy	5	Linked Lists
26	Insert a node at a specific position in a linked list	Solution	Easy	5	Linked Lists
27	Delete a Node	Solution	Easy	5	Linked Lists
28	Print in Reverse	Solution	Easy	5	Linked Lists
29	Reverse a linked list	Solution	Easy	5	Linked Lists
30	Compare two linked lists	Solution	Easy	5	Linked Lists
31	Merge two sorted linked lists	Solution	Easy	5	Linked Lists
32	Get Node Value	Solution	Easy	5	Linked Lists
33	Insert a Node at the Tail of a Linked List	Solution	Easy	5	Linked Lists
34	Print the Elements of a Linked List	Solution	Easy	5	Linked Lists
35	Tree: Preorder Traversal	Solution	Easy	10	Trees
36	Tree: Postorder Traversal	Solution	Easy	10	Trees
37	Tree: Inorder Traversal	Solution	Easy	10	Trees
38	Tree: Height of a Binary Tree	Solution	Easy	10	Trees
39	Tree : Top View	Solution	Easy	20	Trees
40	Tree: Level Order Traversal	Solution	Easy	20	Trees
41	Binary Search Tree : Insertion	Solution	Easy	20	Trees
42	Tree: Huffman Decoding	Solution	Medium	20	Trees
43	Binary Search Tree : Lowest Common Ancestor	Solution	Easy	30	Trees

Tutorials

#	Problem	Solution	Difficulty	Max Score	Sub domain
1	Day 0: Mean, Median, and Mode	Solution	Easy	30	10 Days of Statistics
2	Day 0: Weighted Mean	Solution	Easy	30	10 Days of Statistics
3	Day 1: Quartiles	Solution	Easy	30	10 Days of Statistics
4	Day 1: Interquartile Range	Solution	Easy	30	10 Days of Statistics
5	Day 1: Standard Deviation	Solution	Easy	30	10 Days of Statistics
6	Day 4: Binomial Distribution I	Solution	Easy	30	10 Days of Statistics
7	Day 4: Binomial Distribution II	Solution	Easy	30	10 Days of Statistics
8	Day 4: Geometric Distribution I	Solution	Easy	30	10 Days of Statistics
9	Day 4: Geometric Distribution II	Solution	Easy	30	10 Days of Statistics
10	Day 5: Poisson Distribution I	Solution	Easy	30	10 Days of Statistics
11	Day 5: Poisson Distribution II	Solution	Easy	30	10 Days of Statistics
12	Day 5: Normal Distribution I	Solution	Easy	30	10 Days of Statistics
13	Day 5: Normal Distribution II	Solution	Easy	30	10 Days of Statistics
14	Day 6: The Central Limit Theorem I	Solution	Easy	30	10 Days of Statistics
15	Day 6: The Central Limit Theorem II	Solution	Easy	30	10 Days of Statistics
16	Day 6: The Central Limit Theorem III	Solution	Easy	30	10 Days of Statistics
17	Day 7: Pearson Correlation Coefficient I	Solution	Easy	30	10 Days of Statistics
18	Day 0: Hello, World!	Solution	Easy	10	10 Days of Javascript
19	Day 0: Data Types	Solution	Easy	10	10 Days of Javascript
29	Day 1: Arithmetic Operators	Solution	Easy	10	10 Days of Javascript
30	Day 1: Functions	Solution	Easy	10	10 Days of Javascript
31	Day 1: Let and Const	Solution	Easy	10	10 Days of Javascript
32	Day 2: Loops	Solution	Easy	10	10 Days of Javascript
33	Day 2: Conditional Statements: If-Else	Solution	Easy	10	10 Days of Javascript
34	Day 2: Conditional Statements: Switch	Solution	Easy	10	10 Days of Javascript
35	Day 3: Arrays	Solution	Easy	15	10 Days of Javascript
36	Day 3: Try, Catch, and Finally	Solution	Easy	15	10 Days of Javascript
37	Day 3: Throw	Solution	Easy	15	10 Days of Javascript
38	Day 4: Create a Rectangle Object	Solution	Easy	15	10 Days of Javascript
39	Day 4: Count Objects	Solution	Easy	15	10 Days of Javascript
40	Day 4: Classes	Solution	Easy	15	10 Days of Javascript
41	Day 5: Inheritance	Solution	Easy	15	10 Days of Javascript
42	Day 5: Template Literals	Solution	Easy	15	10 Days of Javascript
43	Day 5: Arrow Functions	Solution	Easy	15	10 Days of Javascript
44	Day 6: Bitwise Operators	Solution	Easy	15	10 Days of Javascript
45	Day 6: JavaScript Dates	Solution	Easy	15	10 Days of Javascript
46	Day 7: Regular Expressions I	Solution	Easy	15	10 Days of Javascript
47	Day 7: Regular Expressions II	Solution	Easy	15	10 Days of Javascript
48	Day 7: Regular Expressions III	Solution	Easy	15	10 Days of Javascript
49	Day 7: Spearman's Rank Correlation Coefficient	Solution	Easy	30	10 Days of Statistics
50	Day 8: Least Square Regression Line	Solution	Easy	30	10 Days of Statistics
51	Day 9: Multiple Linear Regression	Solution	Medium	30	10 Days of Statistics

Mathematics

#	Problem	Solution	Difficulty	Max Score	Sub domain
1	Find the Point	Solution	Easy	5	Fundamentals
2	Maximum Draws	Solution	Easy	5	Fundamentals
3	Handshake	Solution	Easy	10	Fundamentals
4	Minimum Height Triangle	Solution	Easy	10	Fundamentals

SQL

#	Problem	Solution	Difficulty	Max Score	Sub domain
1	Revising the Select Query I	Solution	Easy	10	Basic Select
2	Revising the Select Query II	Solution	Easy	10	Basic Select
3	Select All	Solution	Easy	10	Basic Select
4	Select By ID	Solution	Easy	10	Basic Select
5	Japanese Cities' Attributes	Solution	Easy	10	Basic Select
6	Japanese Cities' Names	Solution	Easy	10	Basic Select
7	Weather Observation Station 1	Solution	Easy	15	Basic Select
8	Weather Observation Station 3	Solution	Easy	10	Basic Select
9	Weather Observation Station 4	Solution	Easy	10	Basic Select
10	Weather Observation Station 5	Solution	Easy	30	Basic Select
11	Weather Observation Station 6	Solution	Easy	10	Basic Select
12	Weather Observation Station 7	Solution	Easy	10	Basic Select
13	Weather Observation Station 8	Solution	Easy	15	Basic Select
14	Weather Observation Station 9	Solution	Easy	10	Basic Select
15	Weather Observation Station 10	Solution	Easy	10	Basic Select
16	Weather Observation Station 11	Solution	Easy	15	Basic Select
17	Weather Observation Station 12	Solution	Easy	15	Basic Select
18	Higher Than 75 Marks	Solution	Easy	15	Basic Select
19	Employee Names	Solution	Easy	10	Basic Select
20	Employee Salaries	Solution	Easy	10	Basic Select
21	Type of Triangle	Solution	Easy	20	Advanced Select
22	The PADS	Solution	Medium	30	Advanced Select
23	Binary Tree Nodes	Solution	Medium	30	Advanced Select
24	New Companies	Solution	Medium	30	Advanced Select
25	Revising Aggregations - The Count Function	Solution	Easy	10	Aggregation
26	Revising Aggregations - The Sum Function	Solution	Easy	10	Aggregation
27	Revising Aggregations - Averages	Solution	Easy	10	Aggregation
28	Average Population	Solution	Easy	10	Aggregation
29	Japan Population	Solution	Easy	10	Aggregation
30	Population Density Difference	Solution	Easy	10	Aggregation
31	The Blunder	Solution	Easy	15	Aggregation
32	Top Earners	Solution	Easy	20	Aggregation
33	Weather Observation Station 2	Solution	Easy	15	Aggregation
34	Weather Observation Station 13	Solution	Easy	10	Aggregation
35	Weather Observation Station 14	Solution	Easy	10	Aggregation
36	Weather Observation Station 15	Solution	Easy	15	Aggregation
37	Weather Observation Station 16	Solution	Easy	10	Aggregation
38	Weather Observation Station 17	Solution	Easy	15	Aggregation
39	Weather Observation Station 18	Solution	Medium	25	Aggregation
40	Weather Observation Station 19	Solution	Medium	30	Aggregation
41	Weather Observation Station 20	Solution	Medium	40	Aggregation
42	Asian Population	Solution	Easy	10	Basic Join
43	African Cities	Solution	Easy	10	Basic Join
44	Average Population of Each Continent	Solution	Easy	10	Basic Join
45	The Report	Solution	Medium	20	Basic Join
46	Top Competitors	Solution	Medium	30	Basic Join
47	Draw The Triangle 1	Solution	Easy	25	Alternative Queries
48	Draw The Triangle 2	Solution	Easy	25	Alternative Queries
49	Ollivander's Inventory	Solution	Medium	30	Basic Join
50	Challenges	Solution	Medium	30	Basic Join
51	Contest Leaderboard	Solution	Medium	30	Basic Join
52	Symmetric Pairs	Solution	Medium	40	Advanced Join
53	Interviews	Solution	Hard	50	Advanced Join
54	15 Days of Learning SQL	Solution	Hard	50	Advanced Join
55	Print Prime Numbers	Solution	Medium	40	Alternative Queries
56	SQL Project Planning	Solution	Medium	40	Advanced Join
57	Placements	Solution	Medium	40	Advanced Join

Interview Preparation Kit

#	Problem	Solution	Difficulty	Max Score	Sub domain
1	Sock Merchant	Solution	Easy	10	Warm-up Challenges
2	Counting Valleys	Solution	Easy	15	Warm-up Challenges
3	Jumping on the Clouds	Solution	Easy	20	Warm-up Challenges
4	Repeated String	Solution	Easy	20	Warm-up Challenges
5	2D Array - DS	Solution	Easy	15	Arrays
6	Array Manipulation	Solution	Hard	60	Arrays
7	Arrays: Left Rotation	Solution	Easy	20	Arrays
8	New Year Chaos	Solution	Medium	40	Arrays
9	Minimum Swaps 2	Solution	Medium	40	Arrays
10	Hash Tables: Ransom Note	Solution	Easy	25	Dictionaries and Hashmaps
11	Hash Tables: Ransom Note	Solution	Easy	25	Dictionaries and Hashmaps
12	Sherlock and Anagrams	Solution	Medium	50	Dictionaries and Hashmaps
13	Count Triplets	Solution	Medium	35	Dictionaries and Hashmaps
14	Frequency Queries	Solution	Medium	40	Dictionaries and Hashmaps
15	Mark and Toys	Solution	Easy	35	Sorting
16	Sorting: Bubble Sort	Solution	Easy	30	Sorting
17	Sorting: Comparator	Solution	Medium	35	Sorting
18	Fraudulent Activity Notifications	Solution	Medium	40	Sorting
19	Merge Sort: Counting Inversions	Solution	Hard	45	Sorting
20	Strings: Making Anagrams	Solution	Easy	25	String Manipulation
21	Alternating Characters	Solution	Easy	20	String Manipulation
22	Sherlock and the Valid String	Solution	Medium	35	String Manipulation
23	Special String Again	Solution	Medium	40	String Manipulation
24	Common Child	Solution	Medium	60	String Manipulation
25	Minimum Absolute Difference in an Array	Solution	Easy	15	Greedy Algorithms
26	Luck Balance	Solution	Easy	20	Greedy Algorithms
27	Greedy Florist	Solution	Medium	35	Greedy Algorithms
28	Max Min	Solution	Medium	35	Greedy Algorithms
29	Hash Tables: Ice Cream Parlor	Solution	Medium	35	Search
30	Pairs	Solution	Medium	50	Search
31	Triple sum	Solution	Medium	40	Search
32	Minimum Time Required	Solution	Medium	35	Search
33	Maximum Subarray Sum	Solution	Hard	65	Search
34	Recursion: Fibonacci Numbers	Solution	Easy	15	Recursion and Backtracking
35	Recursion: Davis' Staircase	Solution	Medium	30	Recursion and Backtracking

C++

#	Problem	Solution	Difficulty	Max Score	Sub domain
1	Say "Hello, World!" With C++	Solution	Easy	5	Introduction
2	Input and Output	Solution	Easy	5	Introduction
3	Basic Data Types	Solution	Easy	10	Introduction
4	Conditional Statements	Solution	Easy	10	Introduction
5	For Loop	Solution	Easy	10	Introduction
6	Functions	Solution	Easy	10	Introduction
7	Pointer	Solution	Easy	10	Introduction
8	Array Introduction	Solution	Easy	10	Introduction
9	Variable Sized Arrays	Solution	Easy	30	Introduction
10	Hotel Prices	Solution	Medium	15	Debugging
11	Cpp exception handling	Solution	Medium	20	Debugging
12	Overloading Ostream Operator	Solution	Medium	20	Debugging
13	Messages Order	Solution	Medium	40	Debugging
14	StringStream	Solution	Easy	10	Strings
15	Strings	Solution	Easy	10	Strings
16	Structs	Solution	Easy	10	Classes
17	Class	Solution	Easy	10	Classes
18	Classes and Objects	Solution	Easy	20	Classes

Artificial Intelligence

#	Problem	Solution	Difficulty	Max Score	Sub domain
1	Bot saves princess	Solution	Easy	13.90	Bot Building
2	Bot saves princess - 2	Solution	Easy	17.50	Bot Building
3	Bot Clean	Solution	Easy	17.82	Bot Building
4	Bot Clean Stochastic	Solution	Easy	10.00	Bot Building
5	BotClean Large	Solution	Hard	54.00	Bot Building
6	BotClean Partially Observable	Solution	Hard	28.00	Bot Building
7	PacMan - DFS	Solution	Easy	15.00	A* Search

Contributing

If you are interested in helping or have a solution in a different language feel free to make a pull request. You can also reach me on through the following media if you want to talk.

• Email - [email protected]
• Let's connect on LinkedIn
• I'm on HackerRank as well