Sphere Online Judge (SPOJ)

list of classical problems

ID	NAME	USERS	ACC %	DIFFICULTY C I
4523	Binomial Coefficients	208	41.44	23 12
4528	Frog Wrestling	66	36.92
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	24.34
4586	Texas Trip	69	38.57
4588	SETI	129	66.41
4657	Gas Wars	142	35.52	34 17
4717	Grid Points in a Triangle	99	46.63
4785	Starship	11	28.46
4828	ZSequence	53	18.80
4881	Words on graphs	106	11.81	34
5011	Library for Madrid	56	42.21	17 17
5014	Crazy Receptionist	11	12.59
5015	Decode the Castanets	33	39.47
5016	Guernica	22	57.45
5018	Street Gambler	27	43.75
5102	Mystic Craft	57	46.20
5103	Top 10	42	15.81
5104	Spam Detection	16	16.52
5115	Two "Ways"	65	15.47
5143	Binary Integer	53	50.00
5144	Cryptography Reloaded (Act I)	34	26.43
5145	Déjà vu	17	15.12
5146	Experiment on a … Cable	14	35.00
5147	Fire-Control System	32	19.43	34 17
5149	History of Languages	30	16.29
5150	Junk-Mail Filter	133	21.46
5153	Compressed String	42	28.41
5154	Cryptography Reloaded (Act II)	32	27.69
5155	Exciting Time	44	13.90
5156	Flowers Placement	43	31.74
5158	Heroes Arrangement	14	11.39
5159	Island Explorer	36	15.49
5160	Jinyuetuan Puzzle	43	35.83
5163	Tower of Vientiane	101	34.19
5182	Double Sorting	15	8.90
5300	Mexican Standoff	21	20.25
5373	Four Mines	14	7.01
5446	Fishing Net	172	31.73
5462	Art Plagiarism	11	24.62
5522	Buy Your House	14	39.13
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
5831	Permutation Jumping	136	59.33
5973	Selecting Teams	229	23.11