Sphere Online Judge (SPOJ)

list of classical problems

ID	NAME	USERS	ACC %	DIFFICULTY C I
2202	Tan and His Interesting Game	42	23.76
2270	Balloons in a Box	169	23.52
2271	Undecodable Codes	46	12.26
2272	Crossing the Desert	50	19.18
2273	Ferries	28	17.39
2275	Toil for Oil	13	30.72
2318	Overlapping Words	88	22.70
2319	Sequence	217	28.09
2323	Broken Compass	41	13.43
2325	String Distance	210	21.18
2413	Building Beacons	41	32.12
2417	Eliminate The Enemies	22	26.55
2418	Flying Frogs	57	37.21
2420	Hospital at Hands	25	23.08	34 34
2423	Minimal Triangulations of Graphs	27	33.33
2485	Phone Lines	18	16.94
2511	Magic Program IV	27	17.99
2631	Chomp	110	45.67
2643	Starcraft I	54	22.25
2658	Art of War	17	17.65
2661	Illumination	6	3.40
2662	Put a Point in a Hyperspace	17	11.06
2709	Untitled Problem	27	17.67
2733	K Equal Digits	10	11.96
2734	Large party	34	23.98
2735	Simplify the Railroad System	57	36.08	17 1
2855	Forest	57	12.14
2877	Another understanding of Super Dice Game	64	10.00
2879	The Cow Doctor	141	37.24	17
2880	Wild West	99	42.47	17 34
2898	Party of Cloaked Killers	29	21.15
2899	Volunteers	55	46.91	17 34
2902	Candy IV	31	50.00	50 34
2903	Transportation	11	38.24
2940	Untitled Problem II	119	15.40	34
2944	Emmons	7	8.28
2962	Painting Blocks (Act I)	108	57.87
3002	Electrophoretic	12	26.00
3005	Subdividing a Land	24	36.90
3009	Revenge of Voronoi	14	35.60
3010	Castle Wall	25	22.13
3078	Copying DNA	43	23.08
3108	Charlesbert and Merangelou	71	47.31
3166	Permutation Exponentiation	33	14.85
3197	Tree Construction	62	19.80
3208	Yet Another Longest Palindrome Problem	68	13.65
3251	Slink	15	44.44	1 1
3254	Guard	14	51.72
3305	Roman Patrollers	46	59.46
3306	Very Special Boxes	110	31.35	9 26