Sphere Online Judge (SPOJ)

list of classical problems

ID	NAME	QUALITY	USERS	ACC %	DIFFICULTY C I
2142	Arranging Flowers		25	9.87
2144	K Edge-disjoint Branchings		9	12.39
2151	Digital Calculator		23	5.69
2153	Internet is Faulty		69	38.54
2154	Kruskal		85	14.03
2159	Delicious Cake		30	14.64
2160	Here-There		30	24.76
2162	Towers of Powers		26	13.87
2171	Ambiguous Codes	1	85	39.47
2177	Galou is back!	-1	226	31.01
2180	Justice League		83	48.97
2185	Musical Optimization	1	73	43.15
2202	Tan and His Interesting Game		46	25.18
2270	Balloons in a Box		172	23.77
2271	Undecodable Codes		48	12.27
2272	Crossing the Desert		54	20.12
2273	Ferries		32	18.75
2275	Toil for Oil		15	28.65
2318	Overlapping Words		90	22.40
2319	Sequence		218	28.12
2323	Broken Compass		47	13.78
2325	String Distance		214	21.51
2413	Building Beacons		42	19.84
2417	Eliminate The Enemies		22	19.74
2418	Flying Frogs		63	35.71
2419	G-Line Grid	1	4	3.31
2423	Minimal Triangulations of Graphs		31	35.09
2485	Phone Lines		19	14.19
2511	Magic Program IV		27	17.99
2631	Chomp		111	45.70
2643	Starcraft I		58	22.30
2658	Art of War		17	14.12
2661	Illumination		10	4.44
2662	Put a Point in a Hyperspace		21	11.79
2709	Untitled Problem		30	16.67
2733	K Equal Digits		16	13.65
2734	Large party		40	26.19
2855	Forest		62	12.68
2877	Another understanding of Super Dice Game		67	10.34
2879	The Cow Doctor		145	33.46	17
2898	Party of Cloaked Killers		28	16.23
2903	Transportation		11	19.12
2940	Untitled Problem II		126	15.45	34
2944	Emmons		7	7.19
2962	Painting Blocks (Act I)		113	57.95
3002	Electrophoretic		15	20.93
3005	Subdividing a Land		28	33.02
3009	Revenge of Voronoi		14	30.26
3010	Castle Wall		26	20.15
3078	Copying DNA		48	21.17