README.md

Easy challenges (82/82)

#	Name	Description	Solution	Test
1	Fizz Buzz	A simple game involving divisibility tests.	✅💾	✅💾
3	Prime Palindrome	Biggest prime palindrome < 1000.	✅💾	✅💾
4	Sum of Primes	Sum of first 1000 primes.	✅💾	✅💾
8	Reverse words	Reversing an input sequence of words.	✅💾	✅💾
18	Multiples of a Number	Multiples of a number greater than another number.	✅💾	✅💾
19	Bit Positions	Bits in position x,y are same or different.	✅💾	✅💾
20	Lowercase	Lowercase text	✅💾	✅💾
21	Sum of Digits	Sum of digits comprising a number	✅💾	✅💾
22	Fibonacci Series	Print out the nth fibonacci number	✅💾	✅💾
23	Multiplication Tables	Print out the grade school multiplication table upto 12*12	✅💾	✅💾
24	Sum of Integers from File	Print the sum of integers read from a file.	✅💾	✅💾
25	Odd Numbers	Print the odd numbers from 1 to 99.	✅💾	✅💾
26	File Size	Print the file size in bytes.	✅💾	✅💾
29	Unique Elements	Extract unique list from a sorted list of numbers.	✅💾	✅💾
30	Set Intersection	Print the intersection of two sets of numbers.	✅💾	✅💾
31	Rightmost Char	Print the position of the rightmost occurrence of a char.	✅💾	✅💾
39	Happy Numbers	Determine if a number is a happy number or not	✅💾	✅💾
40	Self Describing Numbers	Determine if a number is a self-describing number or not	✅💾	✅💾
62	N Mod M	Determine the modulus (without the modulus operator).	✅💾	✅💾
67	Hex to Decimal	Convert a hex number to it's decimal equivalent.	✅💾	✅💾
82	Armstrong Numbers	Determine if a number is an armstrong number.	✅💾	✅💾
83	Beautiful Strings	Facebook Hacker Cup 2013 problem.	✅💾	✅💾
87	Query Board	Set and get values from a matrix using tiny DSL	✅💾	✅💾
91	Simple Sorting	Sort several numbers	✅💾	✅💾
92	Penultimate Word	Find the next-to-last word	✅💾	✅💾
93	Capitalize Words	Capitalize words in a sentence	✅💾	✅💾
96	Swap Case	Swap case in a string	✅💾	✅💾
97	Find a Writer	Find a famous writer in a string	✅💾	✅💾
99	Calculate Distance	Calculate a distance between two points	✅💾	✅💾
100	Even Numbers	Determine if a number is even or not	✅💾	✅💾
102	JSON menu IDs	Calculate IDs in JSON menu	✅💾	✅💾
103	Lowest Unique Number	Find the lowest unique number in a set	✅💾	✅💾
104	Word to Digit	Substitute words to digits	✅💾	✅💾
106	Roman Numerals	Convert a cardinal number to a Roman numeral	✅💾	✅💾
107	Shortest Repetition	Find the shortest repetition in a string	✅💾	✅💾
111	Longest Word	Get the longest word in a sentence	✅💾	✅💾
112	Swap Elements	Swap elements in a list	✅💾	✅💾
113	Multiply Lists	Multiply elements in 2 lists	✅💾	✅💾
115	Mixed Content	Separate words with digits	✅💾	✅💾
116	Morse Code	Decode Morse code	✅💾	✅💾
122	Hidden Digits	Try to look behind the scenes	✅💾	✅💾
124	Road Trip	Do not be left without petrol	✅💾	✅💾
128	Compressed Sequence	Write a program that compresses a sequence of numbers	✅💾	✅💾
131	Split The Number	Evaluate the number according to the pattern	✅💾	✅💾
132	The Major Element	Find the major element in a sequence	✅💾	✅💾
136	Racing Chars	Explore a race track avoiding crashes	✅💾	✅💾
139	Working experience	Retrieve an actual value	✅💾	✅💾
140	Data Recovery	Reconstruct a sentence using hints	✅💾	✅💾
147	Lettercase Percentage Ratio	Find the percentage ratio.	✅💾	✅💾
149	Juggling With Zeros	Convert a zero-based number into integer.	✅💾	✅💾
152	Age distribution	Print out where the person is.	✅💾	✅💾
156	Roller Coaster	Turn the text into RoLlErCoAsTeR case.	✅💾	✅💾
160	Nice angles	Convert angle values to sexagesimal format.	✅💾	✅💾
163	Big Digits	Print out magnified digits using pseudographics.	✅💾	✅💾
166	Delta Time	Find the time difference.	✅💾	✅💾
167	Read More	Limit the length of the text.	✅💾	✅💾
173	Without Repetitions	Delete characters that are consistently repeated.	✅💾	✅💾
174	Slang Flavor	Add some slang to the text.	✅💾	✅💾
179	Matrix Rotation	Rotate a 2D matrix 90 degrees clockwise.	✅💾	✅💾
180	Knight Moves	Find positions for the next move of the knight.	✅💾	✅💾
183	Details	Determine how many cells will be shifted detail.	✅💾	✅💾
186	Max Range Sum	Determine max sum at the range.	✅💾	✅💾
189	Minimum Distance	Find a point with the smallest sum of distances to every given point.	✅💾	✅💾
192	Compare Points	Given two (x, y) points A and B, determine which cardinal direction B is from A.	✅💾	✅💾
196	Swap Numbers	Swap numbers surrounding a word	✅💾	✅💾
199	String mask	Change case letters by mask	✅💾	✅💾
202	Stepwise word	Print the longest word in a stepwise manner	✅💾	✅💾
203	Strings and arrows	Print the number of arrows in a string	✅💾	✅💾
205	Clean up the words	Print the words separated by spaces	✅💾	✅💾
208	Find the highest score	Find the highest rate in the table	✅💾	✅💾
211	Chardonnay or Cabernet	Guess a wine name.	✅💾	✅💾
214	Time to eat	Sort timestamps in the right order.	✅💾	✅💾
217	One zero, two zeros...	Count zeros in a binary system.	✅💾	✅💾
220	Trick or Treat	Count all candies.	✅💾	✅💾
222	Black card	Find the winner.	✅💾	✅💾
225	Testing	Wanna try to be a tester?	✅💾	✅💾
227	Real fake	Check credit card numbers.	✅💾	✅💾
230	Football	Find countries that are football fans.	✅💾	✅💾
232	Not so clever	Simplicity is not always good.	✅💾	✅💾
235	Simple or trump	Check which card is higher.	✅💾	✅💾
237	Panacea - truth or lie	Check whether the virus was stopped by antivirus.	✅💾	✅💾
240	Mersenne prime	Find all Mersenne numbers smaller than n.	✅💾	✅💾

Hard challenges (26/28)

#	Name	Description	Solution	Test
6	Longest Common Subsequence	LCS between two strings.	✅💾	✅💾
7	Prefix expressions	Evaluating a prefix expression.	✅💾	✅💾
14	String Permutations	Print out all permutations of a string.	✅💾	✅💾
28	String Searching	Determine if substring match exists.	✅💾	✅💾
36	Message Decoding	Decode an encoded message	✅💾	✅💾
38	String List	Create a new string from constituent alphabets	✅💾	✅💾
42	Ugly Numbers	Count the number of expressions that can be created from a number	💾	💾
44	Following Integer	Determine the next number in a sequence	✅💾	✅💾
47	Palindromic Ranges	Find out a range of palindromic numbers	✅💾	✅💾
50	String Substitution	Create a new string by replacing substrings within it	✅💾	✅💾
51	Closest Pair	Given a set of points in a two dimensional space, you will have to find the distance between the closest two points.	✅💾	✅💾
52	Text Dollar	Print out the text dollar amount of a given quantity	✅💾	✅💾
56	Robot Movements	Number of ways a robot can reach its destination	✅💾	✅💾
57	Spiral Printing	Print out a 2D array in spiral order	✅💾	✅💾
59	Telephone Words	Print out the words corresponding to a telephone number	✅💾	✅💾
65	Word Search	Find if a word exists in a grid	✅💾	✅💾
72	Minimum Path Sum	Calculate the minimum sum of a path through a matrix.	✅💾	✅💾
79	Minesweeper	Find the mines within a M*N matrix.	✅💾	✅💾
105	Largest Sub-Matrix	Determine the largest sub-matrix in a matrix	✅💾	✅💾
108	Computer Terminal	Print text to terminal with control sequences	✅💾	✅💾
126	Play with DNA	Write an algorithm that a finds DNA segment in a given DNA string	💾	💾
144	Digit statistics	Find statistics in sequence	✅💾	✅💾
155	ASCII Decryption	Decrypt a message.	✅💾	✅💾
157	The Labyrinth	Find the shortest way to exit.	✅💾	✅💾
162	Too unique	Find and mark the biggest submatrices of unique elements.	✅💾	✅💾
210	Brainf*ck	Blow your mind	✅💾	✅💾
213	Lakes, not cakes	Count all lakes.	✅💾	✅💾
216	Everything or nothing	Check if a code is correct.	✅💾	✅💾

Moderate challenges (81/81)

#	Name	Description	Solution	Test
2	Longest Lines	Finding the 'N' longest lines within a file.	✅💾	✅💾
5	Detecting Cycles	Detecting loops within a sequence.	✅💾	✅💾
9	Stack Implementation	Implement a stack interface	✅💾	✅💾
10	Mth to last element	Determine the Mth to last element	✅💾	✅💾
11	Lowest Common Ancestor	Determine the lowest common ancestor within a tree	✅💾	✅💾
12	First Non-Repeated Character	Find the first non repeated character in a string.	✅💾	✅💾
13	Remove Characters	Delete specific characters from a string.	✅💾	✅💾
15	Endianness	Determine the endianness of a system.	✅💾	✅💾
16	Number of Ones	Determine the number of one bits in an integer.	✅💾	✅💾
17	Sum of integers	Determine the largest sum of contiguous integers in an array.	✅💾	✅💾
27	Decimal To Binary	Print the binary representation of a decimal number.	✅💾	✅💾
32	Trailing String	Determine if a string 'B' occurs at the end of string 'A'	✅💾	✅💾
33	Double Squares	FaceBook Hacker Cup 2011: Output the number of ways to write X as the sum of two squares	✅💾	✅💾
34	Number Pairs	Find pairs of numbers in a sorted array whose sum is X	✅💾	✅💾
35	Email Validation	Write a regular expression to validate an email address	✅💾	✅💾
37	Pangrams	Find the missing alphabets	✅💾	✅💾
41	Array Absurdity	Determine if an array contains a duplicated entry	✅💾	✅💾
43	Jolly Jumpers	Determine if a sequence of numbers is a Jolly Jumper	✅💾	✅💾
45	Reverse and Add	Continually add a number to its reverse to arrive at a palindrome	✅💾	✅💾
46	Prime Numbers	Print prime numbers less than N	✅💾	✅💾
54	Cash Register	Determine the amount of change to be returned	✅💾	✅💾
63	Counting Primes	Count the number of primes between two integers.	✅💾	✅💾
66	Pascals Triangle	Print out pascals triangle upto a certain depth.	✅💾	✅💾
68	Valid parentheses	Determine if string is a well-formed parentheses	✅💾	✅💾
70	Overlapping Rectangles	Determine if two rectangles overlap.	✅💾	✅💾
71	Reverse Groups	Reverse elements in a list k items at a time.	✅💾	✅💾
73	Decode Numbers	Count the number of ways to decode a string.	✅💾	✅💾
74	Minimum Coins	Find the minimum number of coins to arrive at a total.	✅💾	✅💾
75	Flavius Josephus	Eliminate every i'th item from a circular list.	✅💾	✅💾
76	String Rotation	Find if a string is the rotation of another string.	✅💾	✅💾
78	Sudoku	Determine if a grid layout is a valid sudoku solution.	✅💾	✅💾
80	URI Comparison	Determine if two URIs match	✅💾	✅💾
81	Sum to Zero	Count of ways in which the sum of four numbers is zero	✅💾	✅💾
84	Balanced Smileys	Facebook Hacker Cup 2013 problem.	✅💾	✅💾
89	Pass Triangle	Lead the way within the triangle	✅💾	✅💾
94	Simple Calculator	Create a simple calculator	✅💾	✅💾
98	Point in Circle	Define whether a point is in a circle	✅💾	✅💾
101	Find a Square	Do 4 points make a square?	✅💾	✅💾
117	A Pile of Bricks	Close a hole in a wall	✅💾	✅💾
119	Chain Inspection	Try to pass a chain	✅💾	✅💾
121	Lost In Translation	Try to become a native speaker	✅💾	✅💾
125	Predict the Number	Try to go beyond the limits	✅💾	✅💾
130	Sequence Transformation	Transform a binary sequence into a string	✅💾	✅💾
133	City Blocks Flyover	Chart the path of a helicopter from above to discover how many city blocks it flew over.	✅💾	✅💾
135	Word chain	Find the longest chain of words	✅💾	✅💾
137	Seek for an Intruder	Find the IP address of an intruder	✅💾	✅💾
138	Car Race	Determine the fastest car	✅💾	✅💾
143	The Ministry of Truth	Your task is to help the Big Brother	✅💾	✅💾
146	Bats Challenge	Count bats on the wire.	✅💾	✅💾
148	Color Code Converter	Determine and convert the color code	✅💾	✅💾
150	Roman and Arabic	Calculate aromatic numbers.	✅💾	✅💾
153	Locks	Calculate unlocked doors.	✅💾	✅💾
158	Interrupted Bubble Sort	Sort a list of elements. Partially.	✅💾	✅💾
161	Game of Life	Implement the classical cellular automaton game.	✅💾	✅💾
165	Suggest Groups	Help your friends to join groups.	✅💾	✅💾
169	Filename Pattern	Filter a list of filenames.	✅💾	✅💾
170	Guess the Number	Guess the number in log2(N) steps.	✅💾	✅💾
172	Card number validation	Check if bank card numbers are valid.	✅💾	✅💾
177	Justify the Text	Align the text to the specified width.	✅💾	✅💾
178	Broken LCD	Determine whether a given number can be displayed on the damaged LCD.	✅💾	✅💾
181	Gronsfeld cipher	Decipher the message enciphered with the Gronsfeld cipher.	✅💾	✅💾
184	Burrows-Wheeler transform	Complete file decompression by inverting BWT.	✅💾	✅💾
187	Consecutive Primes	Determine how many ways the numbers can be arranged such that every consecutive pair sums to a prime.	✅💾	✅💾
190	Number Operations	Determine if it is possible to produce the number 42 with five cards.	✅💾	✅💾
193	Magic Numbers	Print out a list of all the magic numbers in a provided range.	✅💾	✅💾
194	Twenty Forty Eight	Implement the 2048 game logic	✅💾	✅💾
197	Column Names	Convert integer to excel-style column name	✅💾	✅💾
200	Sort matrix columns	Sort matrix columns from lowest to highest numbers	✅💾	✅💾
206	Lucky tickets	Count the lucky tickets	✅💾	✅💾
209	Black or white	Find the smallest submatrix	✅💾	✅💾
212	Robo and Robitta	Count all nuts.	✅💾	✅💾
215	Double trouble	Calculate the number of correct variants for messages.	✅💾	✅💾
218	Builders team.	Count all squares on the map.	✅💾	✅💾
221	Organizational Hierarchy	Recreate the hierarchy tree.	✅💾	✅💾
223	Alternative reality	Count all alternative ways.	✅💾	✅💾
226	Try to solve it	How good decoder are you?	✅💾	✅💾
228	To PI or not to PI	Print a PI number.	✅💾	✅💾
231	Meet Cocktail sort	Learn more about cocktail sort algorithm.	✅💾	✅💾
233	Meet Comb sort	Learn more about the comb sort algorithm.	✅💾	✅💾
236	Beat or bit	Learn more about the Gray code algorithm.	✅💾	✅💾
238	Code combinations	Check whether you can make words from the given letters.	✅💾	✅💾