Sphere Online Judge (SPOJ)

list of classical problems

ID	NAME	USERS	ACC %	DIFFICULTY C I
8286	Perfect Matching	91	19.08	1 17
8316	Win gold medal	55	26.57
8317	Red Balls	44	43.70
8318	color the balls	66	45.75	50 50
8320	Spreadsheet scrolling	78	31.33
8321	Chocolate distribution	115	24.48
8323	Triangle equality	57	41.36
8325	Partitioning the plane	39	41.10
8326	Leaky containers	31	40.82
8327	Progressive progressions	54	62.70
8328	Move the books	27	28.30
8331	Sister cities	39	50.50
8332	Ski slopes	24	20.83
8333	Place-name game	71	36.93
8421	Fun With Inequalities	142	37.43	17 17
8423	Recover Polynomials	53	48.00
8427	Permutation Game	32	38.61
8428	Grid Tiling	24	22.56
8429	Array Sorting	64	16.57
8461	Adventure in Moving	44	28.43	17 17
8478	Ancient Pocket Calculator	7	4.40
8542	Modern Pocket Calculator	35	9.10	28 6
8546	Manoj and Pankaj	51	21.61
8593	Covering the Corral	9	32.50
8594	Tails all the way	291	34.51
8627	I2C	32	24.68
8628	Selling Land	73	48.35
8657	The Bovine Accordion and Banjo Orchestra	7	21.43
8661	Bogosort	43	14.50
8663	Squares Game	34	47.56
8816	Mravograd	29	32.00	17 34
8836	Yet Another Sequence Problem	76	23.64
8844	Detection of Extraterrestrial	119	36.00
8846	Fudan Extracurricular Lives	7	25.00
8848	Herbicide	16	22.37
8849	Imitation	24	36.67
8886	Guess number!	19	5.43	34 34
8945	Grid points (speed variation)	25	23.49
8951	brownie	67	48.82
8971	LQDNUMBERS	33	32.85
8992	A los saltos	38	28.57
9000	Bob and his new kite factory	2	1.38
9030	Bob and his towers	37	30.26
9038	Chessboard Billiard	48	26.35
9063	Shuffling cards	16	30.38
9084	Journey to Mars	101	23.43
9086	Formula 3D	6	10.77
9118	Genetic Fraud	151	29.51
9121	Magical Crafting	57	47.13
9123	Security Zone	36	27.00