Sphere Online Judge (SPOJ)

list of classical problems

ID	NAME	USERS	ACC %	DIFFICULTY C I
3359	Stack	50	16.63
3360	Digital Image Recognition	28	20.48
3373	Permutation Code	43	56.10
3393	Knot or Not	10	16.67
3406	Bases	72	20.81
3412	Higgs Boson	52	19.09
3414	Bora Bora	148	49.39	34 26
3420	Falling Ice	7	12.50
3461	Song Contest	16	15.74
3462	The Skatepark´s New Ramps	11	12.26
3463	Robintron	8	22.06
3465	Drive through MegaCity	24	20.86
3466	Another Longest Common Subsequence Problem	6	5.66
3482	Alias	7	31.82
3483	Begin	4	7.94
3486	Elimination	75	30.31
3490	Hidden Triangle	12	26.87
3492	Braille Transcription	16	14.16	17 17
3495	The Nobel Thief	14	51.52
3533	Game on board	26	31.14
3543	Matrica	56	39.90
3582	Restaurant Tab	24	21.90
3640	Hanoi Subway System Construction	36	40.78
3641	Earthquakes	26	36.14
3642	Pretty Printing	40	22.01
3645	Farthest Headquarters	60	26.80
3646	Adventure Tourism	46	14.43
3647	Moebius	2	2.36
3678	Cattle Bruisers	91	26.33
3733	Trezor	105	52.34
3762	Bread Tree	163	13.66
3867	Who is The Boss	171	25.29
3884	When (You Believe)	24	9.17
3890	Rectangles Counting	175	33.61
3893	Space settlement	67	31.56
3894	Bouncing Balls	28	31.54
3895	Matrix Game	26	21.77
3900	MinCut Query	78	28.99
3901	Black and White Nim	55	39.23
3922	Mystical River	128	25.67
3926	Manhattan Wire	80	14.07
3927	Polygon on the Grid	23	30.34
3929	Different Digits	74	22.75
3935	SHIFT Operator on Matrix	191	42.38
3939	Search of Concatenated Strings	28	24.40
3941	Kth Shortest Path	25	24.30
3942	Cleaning Robot	34	65.28
3961	Journey with Pigs	133	41.31
3965	Minimax Triangulation	60	40.00
3970	Convert to Decimal Base System	56	37.34	17 17