Sphere Online Judge (SPOJ)

ID	NAME	QUALITY	USERS	DIFFICULTY C I
30785	Ada and Apple	12	208	29 23
32952	Ada and Football	3	233	45 39
32223	Ada and Lychees	3	18	42 26
28449	Ada and List	11	335	14 17
32856	Ada and Contact	2	34	34 34
30760	Ada and Travelling Salesman	18	188	23 29
15454	How to Handle the Fans	39	1530	12 11
5832	AND Rounds	51	1701	17 20
27379	Unique Code	22	129	21 21
61	Brackets	178	5541	19 20
14742	Building Bridges(HARD)	10	451	14 17
6168	Building Bridges	27	1663	11 17
23742	Dolan and Nephews	6	55	31 28
33019	Catering Contracts	7	93	23 27
12563	Halt The War	8	400	19 19
13015	Counting Primes	33	1465	16 14
7296	Trees Again	5	168	21 30
9722	Insertion Sort	28	4065	12 12
5296	Air Combat	-1	71	34
10628	Count on a tree	62	2605	32 31
10707	Count on a tree II	70	3527	31 30
11414	Combat on a tree	3	253	28 34
11482	Count on a trie		77	42 50
16245	Living with Courage	20	580	10 13
1108	Card Trick	68	2239	21 24
10810	Its a Murder!	56	2400	16 16
3978	Distance Query	71	1936	24 21
3267	D-query	461	13870	19 23
9577	Dynamic Tree Connectivity	13	650	29 28
1684	Frequent values	112	3980	20 21
18185	Give Away	34	1314	20 19
11985	Gao on a tree	26	867	28 27
12005	Grass Planting	11	604	29 19
1043	Can you answer these queries I	569	14269	25 24
1557	Can you answer these queries II	26	1777	28 35
1716	Can you answer these queries III	236	12028	22 21
2713	Can you answer these queries IV	60	4324	21 21
2916	Can you answer these queries V	52	2861	23 24
4487	Can you answer these queries VI	27	1357	34 28
6779	Can you answer these queries VII	21	1431	38 28
19543	Can you answer these queries VIII	8	214	37 35
132	Help R2-D2!	13	771	19 17
12210	High and Low		65
8002	Horrible Queries	399	11128	19 18
18247	Arrangement Validity	11	223	17 21
18248	Maggu’s Solar Panels	2	49	34 34
26721	I LOVE Kd-TREES III	4	83	34 34
37375	Kingdom of Equality	2	14	26 26
3693	Maximum Sum	59	6602	19 18
8985	Line up	19	411	16 17

#tree

Tree is a data structure that simulates a hierarchical tree structure

https://en.wikipedia.org/wiki/Tree_(data_structure) https://en.wikibooks.org/wiki/Data_Structures/Trees http://www.i-programmer.info/babbages-bag/477-trees.html