Problems

Note that you can solve most task in any order!
Already solved ones are at the bottom of the table.

Tips and Tricks on solving programming puzzles
by Mike Mirzayanov - author of CodeForces

Volume:

Simple Implementation Algorithms Puzzles Special

all tags

Id	Title	Translations	Author	Solved	Blessing
1	Sum "A+B"	DE ES FR AR ZH RO RU SK		56800	1.00
2	Sum in Loop	DE ES FR AR ZH RO RU SK		34524	1.86
3	Sums in Loop	DE ES FR AR ZH RO RU SK		26279	2.34
4	Minimum of Two	DE ES FR AR ZH RO RU SK		22884	2.58
5	Minimum of Three	DE ES FR AR ZH RO RU SK		20498	2.77
15	Maximum of array	DE ES AR ZH RO RU SK		17904	3.01
6	Rounding	DE ES AR ZH RO RU SK		16452	3.15
7	Fahrenheit to Celsius	DE ES AR ZH RO RU SK		15744	3.23
20	Vowel Count	DE ES AR ZH RO RU SK		12771	3.59
11	Sum of digits	DE ES RU ZH SK		12680	3.60
8	Arithmetic Progression	DE ES RU ZH SK		11860	3.72
41	Median of Three	DE ES AR ZH RO RU SK		10879	3.87
9	Triangles	DE ES RU ZH SK		11254	3.81
28	Body Mass Index	DE ES ZH RU SK		10745	3.89
13	Weighted sum of digits	DE ES RU ZH SK		10242	3.98
43	Dice Rolling	DE ES ZH RU SK		9220	4.16
16	Average of an array	DE ES RU SK		9691	4.07
30	Reverse String	DE ES RU SK		9128	4.18
17	Array Checksum	DE ES RU SK		8979	4.20
21	Array Counters	DE ES RU SK		8359	4.33
10	Linear Function	DE ES RU SK		8078	4.39
48	Collatz Sequence	DE ES RU SK		7297	4.56
12	Modulo and time difference	DE ES RU SK		7417	4.54
14	Modular Calculator	ES SK		6856	4.67
27	Bubble Sort	ES RU SK		6193	4.85
26	Greatest Common Divisor	ES SK RU		6031	4.90
18	Square Root	ES RU		5835	4.95
29	Sort with Indexes	RU		5589	5.03
50	Palindromes	DE ES RU SK		5135	5.17
23	Bubble in Array	ES RU		5360	5.10
52	Pythagorean Theorem	RU		4924	5.25
31	Rotate String	ES RU		5117	5.18
67	Fibonacci Sequence	RU		4431	5.43
68	Bicycle Race	ES RU		4403	5.44
57	Smoothing the Weather	ES RU		4429	5.43
24	Neumann's Random Generator	DE ES RU		4783	5.30
35	Savings Calculator			4202	5.52
104	Triangle Area	ES		3500	5.84
25	Linear Congruential Generator	RU		4148	5.55
44	Double Dice Roll	RU		3936	5.64
32	Josephus Problem	RU		4040	5.59
81	Bit Count	RU		3528	5.83
19	Matching Brackets	ES RU		3795	5.70
58	Card Names			3362	5.91
128	Combinations Counting			2772	6.25
47	Caesar Shift Cipher	SK		3443	5.87
49	Rock Paper Scissors			3393	5.89
55	Matching Words			3289	5.95
94	Fool's Day 2014	SK		2876	6.18
59	Bulls and Cows			2973	6.12
61	Prime Numbers Generation	RU		2925	6.15
22	Two Printers	ES RU		3160	6.02
42	Blackjack Counting			2706	6.29
120	Selection Sort			2126	6.71
38	Quadratic Equation			2492	6.43
33	Parity Control	RU		2449	6.46
53	King and Queen			2187	6.66
34	Binary Search			2255	6.60
171	Tree Height Measurement			1520	7.29
37	Mortgage Calculator	ZH		2119	6.71
460	Carlsdale Caverns		csfpython	4	17.22
45	Cards Shuffling	ZH		2065	6.76
69	Fibonacci Divisibility			1932	6.87
63	Integer Factorization	ZH		1850	6.95
46	Tic-Tac-Toe	ZH		1908	6.89
72	Funny Words Generator			1650	7.15
62	Prime Ranges			1690	7.10
121	Insertion Sort			1411	7.42
75	Yacht or Dice Poker			1570	7.23
172	Cloud Altitude Measurement			1150	7.77
127	Anagrams			1312	7.54
39	Share Price Volatility			1575	7.23
134	Flying Text Screensaver			1215	7.68
156	Luhn Algorithm	SK		1045	7.94
114	Tricky Printing			1155	7.77
80	Duel Chances			1183	7.72
459	Number String Multiples of Thirteen		csfpython	5	16.90
36	Code Guesser	UA		1232	7.65
135	Variable Length Code			938	8.13
74	Clock Hands			1109	7.84
105	Convex Polygon Area			966	8.08
54	Pythagorean Triples			1082	7.88
145	Modular Exponentiation			812	8.38
73	Hexagonal Grid			989	8.03
116	Summing Up			842	8.31
97	Girls and Pigs			881	8.24
181	Reverse Polish Notation			623	8.84
187	Static Web Page			602	8.90
98	Azimuth at Treasure Island			767	8.48
188	Basics of HTML			575	8.98
122	QuickSort			709	8.61
85	Rotation in 2D Space			775	8.46
51	Dungeons and Dragons Dice	UA		829	8.34
458	Mountain Panorama		csfpython	5	16.90
56	Life is Simple			802	8.40
428	Broken Keyboard			64	12.77
40	Paths in the Grid	UA		824	8.35
70	Most Frequent Word			730	8.56
66	Caesar Cipher Cracker			732	8.56
88	Pitch and Notes			677	8.69
108	Star Medals			611	8.87
95	Simple Linear Regression			606	8.88
87	Tree Builder			619	8.85
60	Sweet Harvest			656	8.75
77	Point to Segment Distance			615	8.86
211	Information Entropy			387	9.66
86	Brainfuck Interpreter			576	8.97
457	Railroad and Hamilton			5	16.90
207	Suffix Array			378	9.70
91	Game of 2048			540	9.08
71	Fibonacci Divisibility Advanced			567	9.00
176	Say 100			410	9.56
143	Extended Euclidean Algorithm			449	9.40
101	Gradient Calculation			501	9.21
119	Brain Fibo			465	9.34
195	Mul Two			358	9.80
82	Levenshtein Distance			510	9.18
191	Spaceship Weight Fraud			359	9.79
206	Base-32 Encoding			326	9.96
89	Instrument Tuner			474	9.31
64	Maze Pathfinder			496	9.23
429	Moving Average in Time			39	13.61
131	Four Pics One Word			397	9.62
79	Cycles Detection			458	9.37
92	Binary Heap			430	9.48
189	Dynamic Web Page			303	10.09
444	White Rectangle			18	14.90
136	Variable Length Code Unpack			355	9.81
83	Graph Generator			413	9.55
150	Introducing Regexps			336	9.91
126	Sequence of Squares			361	9.78
385	Number of steps in Euclidean Algorithm		gardengnome	81	12.36
90	Lexicographic Permutations			388	9.66
78	Bezier Curves			393	9.64
170	Binary Search in Array			298	10.11
167	Copy Line			301	10.10
301	Skyscraper Price			162	11.17
154	Breadth First Search			309	10.05
197	Loops in Assembly			265	10.32
425	Explosive Breeding			35	13.79
377	Sum of Digits Divisibility			81	12.36
65	Transitive Closure on Candy States			382	9.68
117	Divide by Two			329	9.94
99	Uphill Shooting			344	9.87
144	Modular Inverse			281	10.22
452	Implication in Logic			7	16.41
155	Depth First Search			269	10.29
161	Topological Sorting			262	10.34
453	SR latch			6	16.64
437	Elections and Happiness			20	14.73
174	Calculation of Pi			246	10.45
454	Multiplexer 4x4			5	16.90
455	D flip-flop			4	17.22
133	Billiard Ball			272	10.27
165	Safe Landing			242	10.47
140	Proper Bracket Sequences			260	10.35
76	Pawn Move Validator			311	10.04
433	A Crime on Logic Island		csfpython	21	14.65
447	Fixed Product, Minimum Sum		csfpython	10	15.85
96	Snake Arcade			285	10.19
190	Query String Parameters			205	10.76
184	Matches Picking		quandray	209	10.73
123	Knapsack of Integers			253	10.40
103	Easter Eggs			268	10.30
93	Starving Priority Queue			274	10.26
84	Dijkstra in the Network			277	10.24
130	Combinations with Repetitions			240	10.49
125	Bogosort			238	10.50
173	Chords of Music			201	10.80
366	Image Cutting		oezguery	64	12.77
449	Space Pirates		csfpython	7	16.41
109	Lucky Tickets			233	10.54
146	Color Cubes			207	10.75
323	Next Palindrome		csfpython	89	12.20
151	Word Ladders			199	10.81
371	Pages to Print			55	13.02
129	Enumerating Combinations			204	10.77
399	Methane Identification		moxieman	37	13.70
164	Page Rank			180	10.99
208	Neighborhood of a String			153	11.27
456	Every Third Bit			2	18.11
446	Hangman			8	16.20
139	Beam Balance and Masses			192	10.88
138	Huffman Coding			192	10.88
360	Whisky Blending		csfpython	59	12.90
194	Convex Hull and Farmers			154	11.26
201	Point in Polygon			148	11.32
137	Shannon-Fano Coding			178	11.01
152	RSA Cryptography			169	11.10
199	Employees Web App			141	11.41
337	Introducing Zeckendorf		csfpython	65	12.74
192	Gangster Battles			142	11.40
111	Necklace Count			182	10.97
244	Introducing SQL			109	11.85
329	Roman Arithmetic		csfpython	65	12.74
110	Lucky Tickets Advanced			174	11.05
253	Beautiful Line Chart			99	12.02
368	Number Base Palindrome		csfpython	43	13.44
374	Longest Common Subsequence			40	13.57
168	Caesar meets BF			137	11.46
435	Maze Mapping API-Robot			11	15.70
411	Elo Ratings		moxieman	22	14.57
245	Aggregations in SQL			98	12.03
148	Public Key Cryptography Intro			141	11.41
269	Fibonacci coding			86	12.26
124	Knapsack Backtracking			150	11.30
162	Rubik's Cube			132	11.52
434	A Crime on Logic Island Advanced		csfpython	11	15.70
427	Cheapest Bus Tickets			14	15.31
179	Look and Say binary			123	11.64
106	Random Search Optimization			155	11.24
202	Dancing Pairs			112	11.81
438	Maze Generator			9	16.02
440	Mud Walker			8	16.20
198	Prn Hex Str			111	11.82
214	Sick Travellers			104	11.93
182	Frodo and Black Riders			117	11.73
418	Expected Number of Random Moves		moxieman	17	15.00
372	String Minimization			36	13.74
294	Vigenere Cipher			68	12.66
102	Travelling Salesman			146	11.35
160	Social Web Scraper			121	11.67
177	Nim Game			114	11.77
414	MIDI Variable Length Numbers			18	14.90
364	Arthur Engel's Randomizer			38	13.65
436	Avoid the Grid Points		csfpython	9	16.02
451	Maximize Toy Production		csfpython	3	17.61
158	Hamming Codes			119	11.70
185	Simple 3D Scene			108	11.87
359	Find 3 Numbers		csfpython	39	13.61
246	Joins in SQL			82	12.34
157	Emirp primE			116	11.74
445	Formula 1			5	16.90
442	Chomp			6	16.64
401	Methane Rotation		moxieman	21	14.65
450	Bead Games		csfpython	3	17.61
159	Hard Life			107	11.88
258	Text Justification			70	12.61
400	Memory Check			20	14.73
153	Fermat goes hacking RSA			104	11.93
196	Fibonacci Randomizer			87	12.24
265	Update in SQL			64	12.77
100	Crossing the Road			118	11.72
115	Gradient Descent for SLE			112	11.81
277	The Adventure of Morse Code		zelevin	58	12.93
141	Sliding Window Search			101	11.98
423	Russian Dolls		csfpython	11	15.70
291	Squirrels vs. Acorns		zelevin	52	13.12
384	Equal Hamming Distance		csfpython	23	14.50
281	Basic Tokenizer			55	13.02
186	Simple 3D Scene (cont)			84	12.30
193	Maximum Flow			80	12.38
166	Page Rank as Eigenvector			88	12.22
142	LZ77 decompression			95	12.09
381	Finding Squares		csfpython	23	14.50
407	River Labyrinth			15	15.20
209	Suffix Array Advanced			72	12.56
210	Ticket Puzzle			71	12.59
112	Travelling Salesman Inverted			97	12.05
203	Tic-Tac-Toe Minimax Algorithm			71	12.59
113	Ground Zero			96	12.07
432	Ball Bearing Collisions		csfpython	7	16.41
421	Princess and Tiger			10	15.85
219	Neural Network Calculation			65	12.74
420	Life on a String		csfpython	10	15.85
216	Cracking Linear Congruential Generator			63	12.79
132	Stream Cipher Breaking			84	12.30
351	Nicomachus			27	14.23
274	Two Buckets			46	13.33
163	Colliding Balls			72	12.56
412	Json Fix			11	15.70
107	Knight's Tour			85	12.28
390	Card Pairing Solitaire			16	15.10
175	Algae Robot			67	12.69
406	Wormholes of Cygnus		moxieman	12	15.56
230	Move-To-Front Transform			53	13.09
431	King and Rook Checkmate			6	16.64
448	Button Cycles		csfpython	2	18.11
205	Clustering the Stars			58	12.93
335	Venus Visible			28	14.17
426	Weighted Sum of Digits 2		csfpython	7	16.41
259	Easter Bunnies		gardengnome	45	13.37
241	Village Ways			49	13.22
439	Power Sum of Digits		csfpython	4	17.22
200	Fizz Buzz in Asm			58	12.93
403	Hi-Lo dice game			12	15.56
334	Find all of the SETs		csfpython	27	14.23
293	Sums of Triplets			36	13.74
204	Wandering Star			55	13.02
218	Rain Must Fall	DE		50	13.19
212	BCD to Hex			51	13.15
379	Dice with Infinity Sides		telebashna	16	15.10
315	Count the Common Factors		csfpython	29	14.11
149	Prime Chains			62	12.82
292	Factorial Trailing Zeroes			33	13.89
405	Three Friendly Knights		csfpython	10	15.85
257	Missing Records in SQL			39	13.61
389	Binary Split Guessing Game		csfpython	13	15.43
233	Language Study			43	13.44
409	Election Fever		csfpython	9	16.02
376	Cartesian Tree Visualization			15	15.20
147	Color Cubes Advanced			58	12.93
178	Maze of the Wumpus			52	13.12
118	Maxit Single-Player			62	12.82
307	The Problem of Too Many Clues		zelevin	27	14.23
330	Easter Bunnies Are Back		gardengnome	22	14.57
180	Simple Game of Sticks			48	13.26
223	Introducing Scheme			40	13.57
408	Mad Beaver in River Labyrinth			8	16.20
443	Football League Tables		csfpython	2	18.11
388	Fibonacci Guessing Game			11	15.70
338	Throwing Easter Eggs		gardengnome	19	14.81
393	Urban Planning		csfpython	10	15.85
324	Merge Sort			21	14.65
299	Tree Visualizer			25	14.36
255	LCM of a range			32	13.94
229	Burrows-Wheeler Transform			36	13.74
354	Too Many Divisors		csfpython	16	15.10
247	Towers of Hanoi			33	13.89
183	Connect Four			43	13.44
347	Unwanted Multiples		csfpython	17	15.00
352	Hurkle			16	15.10
416	Socket Server		testuser	6	16.64
297	Collatz in the Range			24	14.43
415	Smallest Message		gardengnome	6	16.64
296	Tree Value	RU	csfpython	24	14.43
375	Space Invaders			12	15.56
386	Advent Calendar Chocolate		gardengnome	10	15.85
270	Hexlife			27	14.23
413	Tree Painting		csfpython	6	16.64
392	Fixing an Anagram			9	16.02
398	Collecting Diamonds		csfpython	8	16.20
363	Language Detector			13	15.43
284	Rotate Array In-Place			24	14.43
340	Zeckendorf Lite		csfpython	16	15.10
290	Every Leaf on Every Tree		zelevin	23	14.50
339	Parking Lot			16	15.10
382	Die Throw Sequences		csfpython	10	15.85
353	Hurkle Hunter			14	15.31
367	Roguelike 1d			12	15.56
287	Palindrome Frog		csfpython	23	14.50
417	Unfortunate Bubble Sort		gardengnome	5	16.90
395	Growth of Micro-Organisms		csfpython	8	16.20
402	Game of Stones		csfpython	7	16.41
238	Bear Hunt			29	14.11
349	Burrows		gardengnome	14	15.31
256	Rook Jump Maze			26	14.29
286	Self-Printing Program			22	14.57
362	Euclid, Manhattan and Chebyshev			12	15.56
217	Personality Swap			31	14.00
331	Rotating Toy Display		csfpython	16	15.10
346	Long Decimal Fractions		csfpython	14	15.31
430	Cutting Paper		csfpython	3	17.61
298	Revoltle		zelevin	20	14.73
243	Grille Encryption			27	14.23
383	E2C2S - try harder!		gardengnome	9	16.02
234	Train Merge			28	14.17
312	The Shredder Conundrum		zelevin	18	14.90
249	Turing Increment			26	14.29
358	Mandelbrot Set			12	15.56
261	Easter Bunnies 2D		gardengnome	24	14.43
357	Ulam's Prime Spiral			12	15.56
169	Automated Landing			35	13.79
282	Predictable Board Game		csfpython	21	14.65
268	Logic Transformation			22	14.57
419	Special Digits		csfpython	4	17.22
300	Run-Length Encoding			18	14.90
410	Village Door Shuffle		csfpython	5	16.90
271	A Knight some Trolls and a Princess		csfpython	21	14.65
313	Seven Segment Decoder			16	15.10
285	Rotate Matrix In Place			19	14.81
361	Rogue Mazes			10	15.85
387	Big Numbers		csfpython	7	16.41
275	Three Buckets			19	14.81
404	Methane Normalization		moxieman	5	16.90
394	Many Shortest Routes		csfpython	6	16.64
250	Turing Clone			21	14.65
344	Throwing Easter Eggs Part 2		gardengnome	11	15.70
422	Mabinogion Sheep		moxieman	3	17.61
213	Micro-Life	SK		24	14.43
441	Max versus Min		csfpython	1	18.81
319	Tower of Hanoi Rules		csfpython	13	15.43
326	Sum Them Forth			12	15.56
220	Neural Network Training			22	14.57
314	The Sorites Solution		zelevin	13	15.43
260	Low Cost Road Network		csfpython	18	14.90
332	Easter Bunnies 2D Are Back		gardengnome	11	15.70
341	Zeckendorf Advanced		csfpython	10	15.85
336	Currency Arbitrage			10	15.85
221	XWords		quandray	20	14.73
289	The Case of the Desperate Mastermind		zelevin	14	15.31
231	Dice Black Jack			19	14.81
380	Treap Study			6	16.64
262	Easter Bunnies 2D Advanced		gardengnome	16	15.10
378	Space Invaders Automation			6	16.64
295	Vigenere Cipher Cracker			13	15.43
306	Line Drawing Algorithm			12	15.56
222	Easter Eggs Advanced			19	14.81
365	Flower Border Arrangements		csfpython	7	16.41
316	Apogee			11	15.70
303	Towers Under Cover			12	15.56
254	Rule 30 by Turing			16	15.10
424	New Towers of Hanoi		csfpython	2	18.11
276	Lucky Pairs		csfpython	14	15.31
288	Langton's Ant		csfpython	13	15.43
263	Easter Bunnies 3D		gardengnome	15	15.20
345	Elliptic Curves Basics			8	16.20
266	Pancake Sorting			14	15.31
343	Village of Ticks			8	16.20
311	The Mirror Maze		zelevin	10	15.85
242	Comment Stripper			15	15.20
309	Board Game Sequences		csfpython	10	15.85
350	Colourful Egg Sequences		gardengnome	7	16.41
279	Two Buckets Advanced		csfpython	12	15.56
391	Scout Proficiency Badges		csfpython	4	17.22
320	Accordion		pearlbarley	9	16.02
235	Train Merge Advanced			15	15.20
333	Happy Triplets			8	16.20
327	Dobbin's Long Journey		csfpython	8	16.20
325	Ultimate Sort Trial			8	16.20
305	The Catacombs of Chronos		zelevin	9	16.02
397	Trading Bot			3	17.61
237	Road Network Destruction			13	15.43
267	Turing Maze			11	15.70
396	Chocolate Triangles and BF		moxieman	3	17.61
328	Beep Beep Beep			7	16.41
227	Hashtable Implementation			13	15.43
310	Board Game Sequences Advanced		csfpython	8	16.20
342	Adaptive Arithmetic Coding			6	16.64
308	Circle Drawing Algorithm			8	16.20
322	Gray Decoder			7	16.41
252	Shadok and Gibis			11	15.70
304	Ordered Brackets		csfpython	8	16.20
215	Klotski	SK		13	15.43
264	Party Presents		csfpython	10	15.85
225	Hamurabi			12	15.56
370	Jewels			4	17.22
369	Flappy Bird			4	17.22
226	Multiplicative Persistence Backtrace			11	15.70
224	Transposing List of Lists			11	15.70
283	Predictable Board Game on 10 Boards		csfpython	8	16.20
321	Hanoi Tower Heights		csfpython	6	16.64
278	Polyomino Generation			8	16.20
251	Radio Spies			9	16.02
355	Robots Game			4	17.22
248	Christmas Puzzle			9	16.02
373	Railroad Rat		csfpython	3	17.61
239	Foxes and Geese			9	16.02
348	Trick-Taking Game			4	17.22
280	Three Buckets Re-visited		csfpython	7	16.41
302	Sound-Controlled Robot			6	16.64
232	Shift Register Randomizer			9	16.02
272	Hexplore			7	16.41
240	Playfair Cipher Cracking			8	16.20
236	Is the Earth Flat			8	16.20
356	Robots Game Autoplay			3	17.61
273	Logic Glitches			6	16.64
317	Launch to Orbit			4	17.22
228	Maze Mapping Robot			6	16.64
318	Launch to Orbit automated			2	18.11