Sphere Online Judge (SPOJ)

list of classical problems

ID	NAME	USERS	ACC %	DIFFICULTY C I
4154	IZBORI	42	26.67
4156	PLAHTE	69	35.77
4160	A1 Road	89	50.90
4178	Distance on a square lattice	130	54.41
4185	Cube	57	35.57
4188	Amazing equality	43	14.08
4202	Brackets Parade	238	45.03
4210	Fast Maximum Matching	19	48.08
4211	Fast Maximum Flow	21	24.62
4212	Another Longest Increasing Subsequence Problem	14	42.50
4225	Payment System	31	61.90
4275	rotate it	40	55.70
4278	Battlefield	8	38.89
4307	Stamps	33	41.94
4308	Byteantean towns	58	24.65
4309	Circular game	35	19.60
4311	Quasi-template	62	34.52
4324	The fate of the pineapple	46	28.98
4361	Connected Points	13	34.78
4378	Twofive	66	26.45
4407	Counting Arborescence	101	34.02
4410	Repair the Door	62	22.96
4411	Counting Expressions	29	31.96
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
4523	Binomial Coefficients	210	41.58	23 12
4528	Frog Wrestling	69	37.50
4533	Determinant of Banded Matrices	21	33.91
4552	Adding up Triangles	140	35.23
4558	I Speak Whales	188	42.51	17 17
4559	A Day at the Races	128	17.79
4574	Riding in cycles	44	23.96
4586	Texas Trip	70	38.84
4588	SETI	130	66.67
4657	Gas Wars	145	35.87	34 17
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
5011	Library for Madrid	59	42.62	17 17
5014	Crazy Receptionist	11	11.11
5015	Decode the Castanets	36	40.68
5016	Guernica	26	61.54
5018	Street Gambler	31	47.83