Sphere Online Judge (SPOJ)

list of classical problems

ID	NAME	USERS	ACC %	DIFFICULTY C I
4478	Counting Expressions II	14	32.14
4523	Binomial Coefficients	208	41.44	23 12
4528	Frog Wrestling	65	39.42
4533	Determinant of Banded Matrices	20	33.33
4552	Adding up Triangles	138	35.96
4558	I Speak Whales	183	42.37	17 17
4559	A Day at the Races	124	17.05
4574	Riding in cycles	42	24.41
4586	Texas Trip	70	38.84
4588	SETI	129	66.41
4657	Gas Wars	142	35.58	34 17
4717	Grid Points in a Triangle	99	46.63
4785	Starship	11	28.46
4828	ZSequence	53	18.59
4881	Words on graphs	105	11.56	34
5011	Library for Madrid	56	42.31	17 17
5014	Crazy Receptionist	11	12.59
5015	Decode the Castanets	32	40.19
5016	Guernica	22	57.45
5018	Street Gambler	27	43.75
5102	Mystic Craft	57	46.20
5103	Top 10	42	16.33
5104	Spam Detection	16	17.62
5115	Two "Ways"	65	15.34
5143	Binary Integer	52	50.00
5144	Cryptography Reloaded (Act I)	34	26.43
5145	Déjà vu	17	16.77
5146	Experiment on a … Cable	13	30.23
5147	Fire-Control System	32	19.43	34 17
5149	History of Languages	30	16.29
5150	Junk-Mail Filter	132	21.37
5153	Compressed String	41	26.92
5154	Cryptography Reloaded (Act II)	32	27.69
5155	Exciting Time	43	13.72
5156	Flowers Placement	43	31.74
5158	Heroes Arrangement	13	12.14
5159	Island Explorer	35	15.31
5160	Jinyuetuan Puzzle	43	35.83
5163	Tower of Vientiane	93	39.87
5182	Double Sorting	15	9.81
5300	Mexican Standoff	21	21.48
5373	Four Mines	14	7.37
5446	Fishing Net	170	31.54
5462	Art Plagiarism	11	24.62
5522	Buy Your House	13	35.71
5523	Highway Patrol	17	41.11
5531	Kutevi Hard	90	43.40
5566	Math with Bases	15	11.06
5637	LL and ErBao	5	46.77
5672	Captain Selection	7	27.03