
Problem Name 
Online Judge 
Contest 
Difficulty Level 
1 
Dquery 
SPOJ 

1 
2 
Mr. Kitayuta's Colorful Graph 
Codeforces 
Codeforces Round #286 (Div. 1) & Codeforces Round #286 (Div. 2) & Codeforces Round #286 (Div. 1) & Codeforces Round #286 (Div. 2) 
2 
3 
GCD 2010 
Timus 

3 
4 
Zero Query 
SPOJ 

3 
5 
Little Elephant and Array 
Codeforces 
Codeforces Round #136 (Div. 1) & Codeforces Round #136 (Div. 2) 
3 
6 
Powerful array 
Codeforces 
Yandex.Algorithm 2011 Round 2 
3 
7 
Gao on a tree 
SPOJ 

3 
8 
XOR and Favorite Number 
Codeforces 
Codeforces Round #340 (Div. 2) 
4 
9 
Xenia and Tree 
Codeforces 
Codeforces Round #199 (Div. 2) 
4 
10 
Little Artem and Time Machine 
Codeforces 
VK Cup 2016  Round 2 
5 
11 
Tree and Queries 
Codeforces 
Codeforces Round #221 (Div. 1) 
5 
12 
DZY Loves Colors 
Codeforces 
Codeforces Round #254 (Div. 1) & Codeforces Round #254 (Div. 2) 
6 
13 
Holidays 
Codeforces 
School Team Contest #2 (Winter Computer School 2010/11) 
6 
14 
Ada and Numbering 
SPOJ 

6 
15 
Holes 
Codeforces 
Codeforces Beta Round #13 
6 
16 
Serega and Fun 
Codeforces 
Codeforces Round #260 (Div. 1) 
6 
17 
Counting diffpairs 
SPOJ 

6 
18 
DZY Loves Fibonacci Numbers 
Codeforces 
Codeforces Round #255 (Div. 1) & Codeforces Round #255 (Div. 2) 
6 
19 
Subset Sums 
Codeforces 
Codeforces Round #202 (Div. 1) & Codeforces Round #202 (Div. 2) 
7 
20 
Conveyor Belts 
Codeforces 
Codeforces Round #278 (Div. 1) 
8 
21 
Ann and Books 
Codeforces 
Codeforces Round #442 (Div. 2) 
8 
22 
Instant Messanger 
Codeforces 
Codeforces Round #233 (Div. 1) 
8 
23 
Jeff and Removing Periods 
Codeforces 
Codeforces Round #204 (Div. 1) 
8 
24 
Destiny 
Codeforces 
Codeforces Round #429 (Div. 1) 
8 