HackerRank

HackerRank hosts challenges to learn, practice, and refine your programming skills. This repository contains my solutions to HackerRank challenges.

Please note that this README is dynamically updated. I created scripts in the automation directory to (1) webscrape challenge information, (2) update this README file, and (3) select challenges to complete and push commits to this repository.

Table of Contents

• SQL
  • Basic Select
  • Advanced Select
  • Aggregation
  • Basic Join
• Statistics
  • 10 Days
• Databases
  • Relational Algebra
  • Indexes
  • OLAP
  • Set And Algebra
• Python
  • Introduction
  • Basic Data Types
  • Strings
  • Sets

SQL

Contains solutions to sql using MySQL.

NOTE: When using Common Table Expressions (CTE), must use the MS SQL Server Console.

Basic Select

Contains solutions to Basic Select.

Number	Challenge	Score	Difficulty	Rate	Solution
1	Revising the Select Query I	10	⭐	96.02%	sql
2	Revising the Select Query II	10	⭐	98.82%	sql
3	Select All	10	⭐	99.69%	sql
4	Select By ID	10	⭐	99.71%	sql
5	Japanese Cities' Attributes	10	⭐	99.69%	sql
6	Japanese Cities' Names	10	⭐	99.72%	sql
7	Weather Observation Station 1	15	⭐	99.53%	sql
8	Weather Observation Station 3	10	⭐	97.48%	sql
9	Weather Observation Station 4	10	⭐	98.55%	sql
10	Weather Observation Station 5	30	⭐	93.24%	sql
11	Weather Observation Station 6	10	⭐	98.45%	sql
12	Weather Observation Station 7	10	⭐	99.10%	sql
13	Weather Observation Station 8	15	⭐	98.62%	sql
14	Weather Observation Station 9	10	⭐	99.17%	sql
15	Weather Observation Station 10	10	⭐	99.47%	sql
16	Weather Observation Station 11	15	⭐	98.51%	sql
17	Weather Observation Station 12	15	⭐	98.79%	sql
18	Higher Than 75 Marks	15	⭐	98.86%	sql
19	Employee Names	10	⭐	99.74%	sql
20	Employee Salaries	10	⭐	99.67%	sql

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Advanced Select

Contains solutions to Advanced Select.

Number	Challenge	Score	Difficulty	Rate	Solution
1	Type of Triangle	20	⭐	95.81%	sql
2	The PADS	30	⭐⭐	93.19%	sql

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Aggregation

Contains solutions to Aggregation.

Number	Challenge	Score	Difficulty	Rate	Solution
1	Revising Aggregations - The Count Function	10	⭐	99.50%	sql
2	Revising Aggregations - The Sum Function	10	⭐	99.64%	sql
3	Revising Aggregations - Averages	10	⭐	99.80%	sql
4	Average Population	10	⭐	99.53%	sql
5	Japan Population	10	⭐	99.86%	sql
6	Population Density Difference	10	⭐	99.84%	sql
7	The Blunder	15	⭐	97.83%	sql
8	Top Earners	20	⭐	97.90%	sql
9	Weather Observation Station 2	15	⭐	99.37%	sql
10	Weather Observation Station 13	10	⭐	99.49%	sql
11	Weather Observation Station 14	10	⭐	99.69%	sql
12	Weather Observation Station 15	15	⭐	98.99%	sql
13	Weather Observation Station 16	10	⭐	99.77%	sql
14	Weather Observation Station 17	15	⭐	99.34%	sql
15	Weather Observation Station 18	25	⭐⭐	98.52%	sql
16	Weather Observation Station 19	30	⭐⭐	98.44%	sql
17	Weather Observation Station 20	40	⭐⭐	96.28%	sql

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Basic Join

Contains solutions to Basic Join.

Number	Challenge	Score	Difficulty	Rate	Solution
1	Asian Population	10	⭐	98.43%	sql
2	African Cities	10	⭐	99.37%	sql
3	Average Population of Each Continent	10	⭐	97.94%	sql
4	The Report	20	⭐⭐	96.98%	sql
5	Top Competitors	30	⭐⭐	96.11%	sql
6	Ollivander's Inventory	30	⭐⭐	94.08%	sql
7	Challenges	30	⭐⭐	92.02%	sql
8	Contest Leaderboard	30	⭐⭐	97.44%	sql

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Statistics

Contains solutions to 10 Days of Statistics.

All solutions (excluding multivariate linear regression) are implemented in Python 3 without using 3rd party statistical libraries. Solutions in .ipynb format include relevant problem notes, formulas, and examples.

NOTE: GitHub does not consistently render .ipynb files. This is a well documented issue. To workaround this issue, access the github url via nbviewer.org in the Solution 2 column.

10_Days

Contains solutions to HackerRank's 10 days of statistics challenge.

Number	Challenge	Score	Difficulty	Rate	Solution	Solution 2
1	Day 0: Mean, Median, and Mode	30	⭐	87.31%	ipynb	nbviewer
2	Day 0: Weighted Mean	30	⭐	96.78%	ipynb	nbviewer
3	Day 1: Quartiles	30	⭐	91.92%	ipynb	nbviewer
4	Day 1: Interquartile Range	30	⭐	93.87%	ipynb	nbviewer
5	Day 1: Standard Deviation	30	⭐	98.77%	ipynb	nbviewer
6	Day 2: Basic Probability	10	MC	69.72%	ipynb	nbviewer
7	Day 2: More Dice	10	MC	84.17%	ipynb	nbviewer
8	Day 2: Compound Event Probability	10	MC	78.13%	ipynb	nbviewer
9	Day 3: Conditional Probability	10	MC	49.26%	ipynb	nbviewer
10	Day 3: Cards of the Same Suit	10	MC	84.13%	ipynb	nbviewer
11	Day 3: Drawing Marbles	10	MC	87.66%	ipynb	nbviewer
12	Day 4: Binomial Distribution I	30	⭐	93.65%	ipynb	nbviewer
13	Day 4: Binomial Distribution II	30	⭐	97.65%	ipynb	nbviewer
14	Day 4: Geometric Distribution I	30	⭐	98.76%	ipynb	nbviewer
15	Day 4: Geometric Distribution II	30	⭐	97.54%	ipynb	nbviewer
16	Day 5: Poisson Distribution I	30	⭐	98.77%	ipynb	nbviewer
17	Day 5: Poisson Distribution II	30	⭐	97.66%	ipynb	nbviewer
18	Day 5: Normal Distribution I	30	⭐	95.55%	ipynb	nbviewer
19	Day 5: Normal Distribution II	30	⭐	97.93%	ipynb	nbviewer
20	Day 6: The Central Limit Theorem I	30	⭐	97.12%	ipynb	nbviewer
21	Day 6: The Central Limit Theorem II	30	⭐	98.84%	ipynb	nbviewer
22	Day 6: The Central Limit Theorem III	30	⭐	97.88%	ipynb	nbviewer
23	Day 7: Pearson Correlation Coefficient I	30	⭐	98.61%	ipynb	nbviewer
24	Day 7: Spearman's Rank Correlation Coefficient	30	⭐	98.83%	ipynb	nbviewer
25	Day 8: Least Square Regression Line	30	⭐	96.66%	ipynb	nbviewer
26	Day 8: Pearson Correlation Coefficient II	30	MC	57.60%	ipynb	nbviewer
27	Day 9: Multiple Linear Regression	30	⭐⭐	95.59%	ipynb	nbviewer

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Databases

Contains solutions to HackerRank's databases challenges.

Relational Algebra

Contains solutions to HackerRank's databases Relational Algebra challenges.

Relational Algebra

relational algebra is to provide a theoretical foundation for relational databases, particularly query languages for such databases, chief among which is SQL. Relational databases store tabular data represented as relations. Queries over relational databases often likewise return tabular data represented as relations. The main premise of the relational algebra is to define operators that transform one or more input relations to an output relation.

Number	Challenge	Score	Difficulty	Rate	Solution
1	Basics of Sets and Relations #1	5	⭐	90.73%	md
2	Basics of Sets and Relations #2	5	⭐	97.48%	md
3	Basics of Sets and Relations #3	5	⭐	97.40%	md
4	Basics of Sets and Relations #4	5	⭐	96.91%	md
5	Basics of Sets and Relations #5	5	⭐	97.79%	md
6	Basics of Sets and Relations #6	5	⭐	97.02%	md
7	Basics of Sets and Relations #7	5	⭐	98.24%	md
8	Relational Algebra - 3	2	MC	67.45%	md
9	Relational Algebra - 4	2	MC	62.70%	md
10	Database Query Languages	2	MC	84.37%	md
11	Procedural Language	2	MC	46.76%	md
12	Relations - 1	2	MC	68.18%	md
13	Relations - 2	2	MC	74.00%	md

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Indexes

Contains solutions to Indexes.

Database Index

A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure.

Number	Challenge	Score	Difficulty	Rate	Solution
1	Index Architecture Types	2	-	61.20%	md
2	Indexes - 2	2	MC	51.46%	md
3	Indexes - 3	2	MC	50.44%	md
4	Indexes - 4	2	MC	69.61%	md

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OLAP

Contains solutions to HackerRank's OLAP challenges.

OLAP

Online analytical processing is an approach to answer multi-dimensional analytical (MDA) queries swiftly in computing. OLAP is part of the broader category of business intelligence, which also encompasses relational databases, report writing and data mining. OLAP tools enable users to analyze multidimensional data interactively from multiple perspectives

Number	Challenge	Score	Difficulty	Rate	Solution
1	OLAP Performance	5	-	74.77%	md
2	OLAP Operations - 1	5	MC	43.92%	md
3	OLAP Operations - 2	5	MC	65.58%	md
4	OLAP Cube Metadata	5	MC	63.26%	md
5	OLAP Name(s)	5	MC	60.87%	md
6	The Total View	5	MC	55.59%	md

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Set And Algebra

Contains solutions to Set and Algebra.

Number	Challenge	Score	Difficulty	Rate	Solution
1	Databases - Relational Calculus	5	⭐⭐	84.56%	md
2	Databases - Keys	5	⭐⭐	97.91%	md
3	Databases - Natural Joins	5	⭐⭐	95.39%	md
4	Databases - Differences	5	⭐⭐	96.96%	md

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Python

Contains solutions to HackerRank's python challenges using Python3.

Introduction

Contains solutions to introduction.

Number	Challenge	Score	Difficulty	Rate	Solution
1	Say "Hello, World!" With Python	5	⭐	97.62%	py
2	Python If-Else	10	⭐	91.31%	py
3	Arithmetic Operators	10	⭐	98.44%	py
4	Python: Division	10	⭐	98.87%	py
5	Loops	10	⭐	98.48%	py
6	Write a function	10	⭐⭐	90.61%	py
7	Print Function	20	⭐	96.50%	py

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Basic Data Types

Contains solutions to Basic Data Types.

Number	Challenge	Score	Difficulty	Rate	Solution
1	List Comprehensions	10	⭐	98.27%	py
2	Find the Runner-Up Score!	10	⭐	93.80%	py
3	Nested Lists	10	⭐	90.65%	py
4	Finding the percentage	10	⭐	97.34%	py
6	Tuples	10	⭐	98.40%	py

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Strings

Contains solutions to Strings.

Number	Challenge	Score	Difficulty	Rate	Solution
1	sWAP cASE	10	⭐	98.63%	py
2	String Split and Join	10	⭐	98.88%	py
3	What's Your Name?	10	⭐	97.87%	py
4	Mutations	10	⭐	98.54%	py
5	Find a string	10	⭐	93.24%	py
6	String Validators	10	⭐	93.34%	py
7	Text Alignment	10	⭐	97.67%	py
8	Text Wrap	10	⭐	98.74%	py
9	Designer Door Mat	10	⭐	98.28%	py
10	String Formatting	10	⭐	90.21%	py
11	Alphabet Rangoli	20	⭐	96.74%	py
12	Capitalize!	20	⭐	82.59%	py
13	The Minion Game	40	⭐⭐	85.06%	py
14	Merge the Tools!	40	⭐⭐	92.11%	py

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Sets

Contains solutions to Sets.

Number	Challenge	Score	Difficulty	Rate	Solution
1	Introduction to Sets	10	⭐	98.51%	py
2	No Idea!	50	⭐⭐	85.81%	py
3	Symmetric Difference	10	⭐	97.89%	py
4	Set .add()	10	⭐	99.18%	py
5	Set .discard(), .remove() & .pop()	10	⭐	96.32%	py
6	Set .union() Operation	10	⭐	99.19%	py
7	Set .intersection() Operation	10	-	99.51%	py
8	Set .difference() Operation	10	-	99.41%	py
9	Set .symmetric_difference() Operation	10	⭐	99.50%	py
10	Set Mutations	10	⭐	98.24%	py
11	The Captain's Room	10	⭐	89.99%	py
12	Check Subset	10	⭐	98.65%	py

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