Sphere Online Judge (SPOJ)

list of classical problems

ID	NAME	QUALITY	USERS	ACC %	DIFFICULTY C I
4407	Counting Arborescence		101	34.02
4409	Circle vs Triangle	1	61	19.83
4410	Repair the Door		62	22.96
4411	Counting Expressions		29	31.96
4412	Factorization, Factorization, Factorization	1	56	41.44
4420	Counting Graphs		76	36.64
4421	Irreducible polynomials over GF2		64	18.04
4453	Bouncing Balls II		227	27.98
4455	Going to the Movies		89	36.79
4459	Muzidabutur		34	26.62
4461	A Famous Airport Manager		27	17.18
4477	Flower growing		117	22.21
4478	Counting Expressions II		14	17.65
4528	Frog Wrestling		69	37.50
4533	Determinant of Banded Matrices		21	33.91
4551	Match Maker	1	63	22.91
4552	Adding up Triangles		140	35.23
4559	A Day at the Races		128	17.79
4574	Riding in cycles		44	23.96
4585	Star Wars	1	76	36.63
4586	Texas Trip		70	38.84
4588	SETI		130	66.67
4717	Grid Points in a Triangle		99	46.63
4785	Starship		16	31.25
4828	ZSequence		53	18.02
4881	Words on graphs		108	11.94	34
5014	Crazy Receptionist		11	11.72
5015	Decode the Castanets		36	40.68
5016	Guernica		26	61.54
5018	Street Gambler		31	47.83
5093	Pretty Functions	1	43	22.67
5102	Mystic Craft		57	46.20
5103	Top 10		43	15.98
5104	Spam Detection		16	15.97
5115	Two "Ways"		67	15.62
5143	Binary Integer		53	50.00
5144	Cryptography Reloaded (Act I)		34	26.43
5145	Déjà vu		17	14.94
5146	Experiment on a … Cable		16	36.36
5149	History of Languages		32	17.70
5150	Junk-Mail Filter		146	22.49
5153	Compressed String		46	28.21
5154	Cryptography Reloaded (Act II)		36	27.49
5155	Exciting Time		45	13.96
5156	Flowers Placement		43	31.33
5158	Heroes Arrangement		17	12.94
5159	Island Explorer		37	16.00
5160	Jinyuetuan Puzzle		45	37.70
5163	Tower of Vientiane		105	34.94
5182	Double Sorting		15	8.70