1 
P1  Queries about less or equal elements 
Codeforces 
Educational Codeforces Round 2 
2 
P2  Hamburgers 
Codeforces 
Codeforces Round #218 (Div. 2) 
3 
P3  K12  Building Construction 
SPOJ 

4 
P4  Devu and his Brother 
Codeforces 
Codeforces Round #251 (Div. 2) 
5 
P5  Subset Sums 
SPOJ 

6 
P6  Anya and Cubes 
Codeforces 
Codeforces Round #297 (Div. 2) 
7 
P7  Cellular Network 
Codeforces 
Educational Codeforces Round 15 
8 
P8  Bars 
UVA 

9 
P9  Grid Game 
UVA 

10 
P10  Heroes 
Codeforces 
Codeforces Beta Round #69 (Div. 1 Only) & Codeforces Beta Round #69 (Div. 2 Only) 
11 
P11  KDominant Character 
Codeforces 
Educational Codeforces Round 32 
12 
P12  They Are Everywhere 
Codeforces 
Codeforces Round #364 (Div. 2) 
13 
P13  Polo the Penguin and Matrix 
Codeforces 
Codeforces Round #177 (Div. 2) 