combinatorics problems

Problem Name Online Judge Year Contest Difficulty Level
1 Marbles SPOJ 1
2 Combinations UVA 1
3 Wooden Sticks PKU 1
4 Number Sequence PKU 1
5 DNA Sorting PKU 1
6 Cipher PKU 1
7 Round Numbers PKU 1
8 Paths on a Grid PKU 1
9 Permutations SPOJ 1
10 Triangle Counting UVA 1
11 Brick Wall Patterns UVA 1
12 Lucky Numbers Codeforces Experimental Educational Round: VolBIT Formulas Blitz 1
13 Wet Shark and Bishops Codeforces Codeforces Round #341 (Div. 2) 1
14 Chocolate Codeforces Codeforces Round #340 (Div. 2) 1
15 Pasha and Stick Codeforces Codeforces Round #337 (Div. 2) 1
16 Random Teams Codeforces Codeforces Round #273 (Div. 2) 1
17 Dreamoon and WiFi Codeforces Codeforces Round #272 (Div. 2) 1
18 Mashmokh and ACM Codeforces Codeforces Round #240 (Div. 1) & Codeforces Round #240 (Div. 2) 1
19 Pocket Book Codeforces Codeforces Round #108 (Div. 2) 2
20 The World is a Theatre Codeforces Codeforces Beta Round #95 (Div. 2) 2
21 Permutations UVA 2
22 Yet another Number Sequence UVA 2
23 Choose and divide UVA 2
24 Safe Salutations UVA 2
25 Count the Trees UVA 2
26 How many nodes ? UVA 2
27 How Many Trees? UVA 2
28 Trees Made to Order PKU 2
29 Code PKU 2
30 Necklace of Beads PKU 2
31 Let it Bead PKU 2
32 Color PKU 2
33 Candy Distribution PKU 2
34 Ciel and Flowers Codeforces Codeforces Round #190 (Div. 2) 2
35 Kolya and Tanya Codeforces Codeforces Round #324 (Div. 2) 2
36 Modulo Sum Codeforces Codeforces Round #319 (Div. 2) 2
37 Kyoya and Colored Balls Codeforces Codeforces Round #309 (Div. 1) & Codeforces Round #309 (Div. 2) 2
38 Points on Line Codeforces Codeforces Round #153 (Div. 1) & Codeforces Round #153 (Div. 2) 2
39 Mr. Kitayuta's Gift Codeforces Codeforces Round #286 (Div. 1) & Codeforces Round #286 (Div. 2) & Codeforces Round #286 (Div. 1) & Codeforces Round #286 (Div. 2) 2
40 Leha and Function Codeforces Codeforces Round #429 (Div. 1) & Codeforces Round #429 (Div. 2) 2
41 Little Elephant and Interval Codeforces Codeforces Round #129 (Div. 1) & Codeforces Round #129 (Div. 2) 3
42 Card Game SPOJ 3
43 Burger UVA 3
44 Binomial Theorem UVA 3
45 Expression Bracketing UVA 3
46 A decorative fence PKU 3
47 Lucky tickets PKU 3
48 Cow Sorting PKU 3
49 Magic Bracelet PKU 3
50 Connected Graph PKU 3
51 Longge's problem PKU 3
52 Selection of Personnel Codeforces Experimental Educational Round: VolBIT Formulas Blitz 3
53 Hamming Distance Sum Codeforces Codeforces Round #336 (Div. 2) 3
54 Ilya and Escalator Codeforces Codeforces Round #293 (Div. 2) 3
55 Unbearable Controversy of Being Codeforces Codeforces Round #277.5 (Div. 2) 3
56 Pashmak and Buses Codeforces Codeforces Round #261 (Div. 2) 3
57 Star Codeforces April Fools Day Contest 4
58 Quantity of Strings Codeforces Codeforces Round #107 (Div. 1) & Codeforces Round #107 (Div. 2) 4
59 Dima and Sequence Codeforces Codeforces Round #167 (Div. 2) 4
60 FUN WITH NUMBERS SPOJ 4
61 CARDS PKU 4
62 Leonardo's Notebook PKU 4
63 The Stable Marriage Problem PKU 4
64 Difference between Triplets PKU 4
65 Weather Codeforces Codeforces Round #145 (Div. 2, ACM-ICPC Rules) 4
66 Benches Codeforces Experimental Educational Round: VolBIT Formulas Blitz 4
67 Gerald and Giant Chess Codeforces Codeforces Round #313 (Div. 1) & Codeforces Round #313 (Div. 2) 4
68 Vanya and Triangles Codeforces Codeforces Round #308 (Div. 2) 4
69 New Year Santa Network Codeforces Good Bye 2014 4
70 Inna and Nine Codeforces Codeforces Round #220 (Div. 2) 4
71 Matrix Codeforces Codeforces Round #213 (Div. 1) & Codeforces Round #213 (Div. 2) 4
72 Tourist Problem Codeforces Codeforces Round #198 (Div. 2) & Codeforces Round #198 (Div. 1) 4
73 Magic Five Codeforces Codeforces Round #191 (Div. 2) 4
74 Beautiful Numbers Codeforces Codeforces Round #181 (Div. 2) 4
75 Polo the Penguin and Houses Codeforces Codeforces Round #177 (Div. 1) 4
76 The Intriguing Obsession Codeforces Codeforces Round #439 (Div. 2) 4
77 Ralph And His Magic Field Codeforces Codeforces Round #447 (Div. 2) 4
78 Directed Roads Codeforces Codeforces Round #369 (Div. 2) 4
79 Cycles Codeforces Codeforces Round #144 (Div. 1) & Codeforces Round #144 (Div. 2) 5
80 Games with Rectangle Codeforces Codeforces Beta Round #94 (Div. 1 Only) & Codeforces Beta Round #94 (Div. 2 Only) 5
81 Permutations Codeforces Codeforces Beta Round #92 (Div. 2 Only) 5
82 Basketball Team Codeforces Codeforces Beta Round #83 (Div. 1 Only) & Codeforces Beta Round #83 (Div. 2 Only) 5
83 How many trees? Codeforces Codeforces Beta Round #9 (Div. 2 Only) 5
84 Prime Factors Live Archive 1997 North America - East Central NA 5
85 The shuffle Problem PKU 5
86 Regetni PKU 5
87 Jerry's Protest Codeforces 8VC Venture Cup 2016 - Elimination Round 5
88 Lengthening Sticks Codeforces Codeforces Round #317 [AimFund Thanks-Round] (Div. 1) & Codeforces Round #317 [AimFund Thanks-Round] (Div. 2) 5
89 Symmetric and Transitive Codeforces Codeforces Round #315 (Div. 1) & Codeforces Round #315 (Div. 2) 5
90 Vitaly and Cycle Codeforces Codeforces Round #311 (Div. 2) 5
91 Kyoya and Permutation Codeforces Codeforces Round #309 (Div. 1) & Codeforces Round #309 (Div. 2) 5
92 Increase Sequence Codeforces Codeforces Round #266 (Div. 2) 5
93 Mashmokh and Reverse Operation Codeforces Codeforces Round #240 (Div. 1) & Codeforces Round #240 (Div. 2) 5
94 Roman and Numbers Codeforces Codeforces Round #235 (Div. 2) 5
95 Two Heaps Codeforces Codeforces Round #205 (Div. 2) 5
96 Jeff and Furik Codeforces Codeforces Round #204 (Div. 1) & Codeforces Round #204 (Div. 2) 5
97 Iahub and Permutations Codeforces Codeforces Round #198 (Div. 2) & Codeforces Round #198 (Div. 1) 5
98 Malek Dance Club Codeforces Codeforces Round #189 (Div. 1) & Codeforces Round #189 (Div. 2) 5
99 Shaass and Lights Codeforces Codeforces Round #178 (Div. 2) 5
100 Dima and Two Sequences Codeforces Codeforces Round #167 (Div. 2) & Codeforces Round #167 (Div. 1) 5
101 Weird journey Codeforces Codeforces Round #407 (Div. 1) & Codeforces Round #407 (Div. 2) 5
102 Square Subsets Codeforces Codeforces Round #448 (Div. 2) 5
103 Winter is here Codeforces Codeforces Round #428 (Div. 2) 5
104 Anton and School - 2 Codeforces Codeforces Round #404 (Div. 2) 5
105 Little Elephant and Elections Codeforces Codeforces Round #157 (Div. 1) & Codeforces Round #157 (Div. 2) 6
106 Table Codeforces Codeforces Round #144 (Div. 1) & Codeforces Round #144 (Div. 2) 6
107 Triangles Codeforces Codeforces Round #142 (Div. 1) & Codeforces Round #142 (Div. 2) 6
108 Partial Sums Codeforces Codeforces Round #138 (Div. 1) & Codeforces Round #138 (Div. 2) 6
109 Numbers Codeforces Codeforces Round #131 (Div. 1) & Codeforces Round #131 (Div. 2) 6
110 Cipher Codeforces Codeforces Round #110 (Div. 1) & Codeforces Round #110 (Div. 2) 6
111 Lucky Subsequence Codeforces Codeforces Round #104 (Div. 1) & Codeforces Round #104 (Div. 2) 6
112 Lucky Permutation Codeforces Codeforces Beta Round #91 (Div. 1 Only) & Codeforces Beta Round #91 (Div. 2 Only) 6
113 Array Codeforces Codeforces Beta Round #53 6
114 ETS Problem setting UVA 6
115 Birthday Cake PKU 6
116 Sum of powers PKU 6
117 Parking Lot Codeforces Experimental Educational Round: VolBIT Formulas Blitz 6
118 Challenge Pennants Codeforces Experimental Educational Round: VolBIT Formulas Blitz 6
119 Bots Codeforces Bubble Cup 8 - Finals [Online Mirror] 6
120 Pig and Palindromes Codeforces Codeforces Round #316 (Div. 2) 6
121 GukiZ and Binary Operations Codeforces Codeforces Round #307 (Div. 2) 6
122 Pluses everywhere Codeforces Codeforces Round #295 (Div. 2) & Codeforces Round #295 (Div. 1) 6
123 Special Matrices Codeforces Codeforces Round #277.5 (Div. 2) 6
124 Magic Trick Codeforces MemSQL Start[c]UP 2.0 - Round 1 6
125 Devu and Flowers Codeforces Codeforces Round #258 (Div. 2) 6
126 Jzzhu and Numbers Codeforces Codeforces Round #257 (Div. 1) 6
127 Random Task Codeforces Codeforces Round #247 (Div. 2) 6
128 Compartments Codeforces Codeforces Round #207 (Div. 1) & Codeforces Round #207 (Div. 2) 6
129 Greg and Friends Codeforces Codeforces Round #179 (Div. 1) & Codeforces Round #179 (Div. 2) 6
130 Permutation Sum Codeforces Codeforces Round #175 (Div. 2) 6
131 Little Elephant and LCM Codeforces Codeforces Round #157 (Div. 1) & Codeforces Round #157 (Div. 2) 6
132 Unusual Sequences Codeforces Codeforces Round #450 (Div. 2) 6
133 Mike and Geometry Problem Codeforces Codeforces Round #361 (Div. 2) 6
134 Memory and Scores Codeforces Codeforces Round #370 (Div. 2) 6
135 The table Codeforces Codeforces Round #140 (Div. 1) 7
136 Chessboard Billiard Codeforces Codeforces Beta Round #68 7
137 Right Triangles Codeforces Codeforces Testing Round #1 7
138 On Number of Decompositions into Multipliers Codeforces Codeforces Round #232 (Div. 1) & Codeforces Round #232 (Div. 2) 7
139 Plato's Blocks PKU 7
140 ????? PKU 7
141 Fence Divercity Codeforces Codeforces Round #346 (Div. 2) 7
142 Square Root of Permutation Codeforces Educational Codeforces Round 4 7
143 Devu and Birthday Celebration Codeforces Codeforces Round #251 (Div. 2) 7
144 Beautiful Pairs of Numbers Codeforces Codeforces Round #236 (Div. 1) 7
145 Levko and Strings Codeforces Codeforces Round #210 (Div. 1) & Codeforces Round #210 (Div. 2) 7
146 Vasily the Bear and Beautiful Strings Codeforces Codeforces Round #195 (Div. 2) 7
147 Axis Walking Codeforces Codeforces Round #191 (Div. 2) 7
148 Yaroslav and Two Strings Codeforces Codeforces Round #179 (Div. 2) 7
149 Dima and Horses Codeforces Codeforces Round #167 (Div. 2) & Codeforces Round #167 (Div. 1) 7
150 Ski Base Codeforces Codeforces Beta Round #75 (Div. 1 Only) & Codeforces Beta Round #75 (Div. 2 Only) 7
151 On the Bench Codeforces Codeforces Round #429 (Div. 1) & Codeforces Round #429 (Div. 2) 7
152 String Mark Codeforces Codeforces Round #448 (Div. 2) 7
153 Number Challenge Codeforces Codeforces Round #146 (Div. 1) 8
154 Gifts Codeforces Codeforces Round #142 (Div. 1) 8
155 Periodical Numbers Codeforces Codeforces Round #132 (Div. 2) 8
156 Playing with Superglue Codeforces Croc Champ 2012 - Round 2 8
157 Clues Codeforces Codeforces Round #110 (Div. 1) 8
158 New Year Garland Codeforces Codeforces Round #100 8
159 Brackets Codeforces Codeforces Beta Round #92 (Div. 1 Only) & Codeforces Beta Round #92 (Div. 2 Only) 8
160 Petya and Coloring Codeforces Codeforces Beta Round #85 (Div. 1 Only) 8
161 Bath Queue Codeforces Codeforces Beta Round #28 (Codeforces format) 8
162 Tickets Codeforces Codeforces Beta Round #26 (Codeforces format) 8
163 Parquet Codeforces Codeforces Beta Round #26 (Codeforces format) 8
164 Positions in Permutations Codeforces Codeforces Round #175 (Div. 2) 8
165 Hexagonal Routes PKU 8
166 Different Subsets For All Tuples Codeforces Educational Codeforces Round 11 8
167 Cowslip Collections Codeforces CROC 2016 - Elimination Round 8
168 Misha and Palindrome Degree Codeforces Codeforces Round #285 (Div. 2) & Codeforces Round #285 (Div. 1) 8
169 The Child and Binary Tree Codeforces Codeforces Round #250 (Div. 1) 8
170 Vowels Codeforces Codeforces Round #225 (Div. 1) 8
171 Sereja and Intervals Codeforces Codeforces Round #215 (Div. 1) 8
172 Black-and-White Cube Codeforces Testing Round #7 8
173 Olya and Graph Codeforces Codeforces Round #184 (Div. 2) 8
174 Greg and Caves Codeforces Codeforces Round #179 (Div. 1) 8
175 Distinct Paths Codeforces Croc Champ 2013 - Round 2 8
176 Polo the Penguin and Trees Codeforces Codeforces Round #177 (Div. 1) 8
177 Cow Tennis Tournament Codeforces Codeforces Round #174 (Div. 1) 8
178 Number Table Codeforces Codeforces Beta Round #39 8
179 Codeword Codeforces Codeforces Round #349 (Div. 1) 8
180 Find a car Codeforces Codeforces Round #415 (Div. 1) & Codeforces Round #415 (Div. 2) 8
181 An unavoidable detour for home Codeforces Codeforces Round #418 (Div. 2) 8
182 Little Elephant and Triangle Codeforces Codeforces Round #136 (Div. 1) 9
183 Bitonix' Patrol Codeforces Codeforces Round #134 (Div. 1) 9
184 Thoroughly Bureaucratic Organization Codeforces Codeforces Round #127 (Div. 1) 9
185 Lucky Pair Codeforces Codeforces Round #104 (Div. 1) 9
186 Pentagon Codeforces Codeforces Beta Round #48 9
187 Lesson Timetable Codeforces Codeforces Beta Round #37 9
188 Triangles Codeforces Codeforces Beta Round #15 9
189 Flags Codeforces Codeforces Beta Round #76 (Div. 1 Only) 9
190 Move by Prime Codeforces IndiaHacks 2016 - Online Edition (Div. 1 + Div. 2) 9
191 Transforming Sequence Codeforces AIM Tech Round (Div. 1) 9
192 Present for Vitalik the Philatelist Codeforces Codeforces Round #325 (Div. 1) 9
193 Randomizer Codeforces Codeforces Round #313 (Div. 1) 9
194 Pasha and Pipe Codeforces Codeforces Round #293 (Div. 2) 9
195 Random Function and Tree Codeforces Codeforces Round #275 (Div. 1) 9
196 On Sum of Number of Inversions in Permutations Codeforces Codeforces Round #232 (Div. 1) 9
197 Yet Another Number Sequence Codeforces Codeforces Round #230 (Div. 1) & Codeforces Round #230 (Div. 2) 9
198 Ksenia and Combinatorics Codeforces Codeforces Round #224 (Div. 2) 9
199 Sereja and Cinema Codeforces Codeforces Round #223 (Div. 1) 9
200 The Red Button Codeforces MemSQL start[c]up Round 1 9
201 White, Black and White Again Codeforces Testing Round #6 9
202 Research Rover Codeforces Intel Code Challenge Elimination Round (Div. 1 + Div. 2, combined) 9
203 Singer House Codeforces Codeforces Round #424 (Div. 1, rated, based on VK Cup Finals) 9
204 Karen and Cards Codeforces Codeforces Round #419 (Div. 1) 9
205 Lust Codeforces Codeforces Round #446 (Div. 1) 9
206 Weak Subsequence Codeforces Codeforces Beta Round #97 (Div. 1) 10
207 Sleeping Codeforces Codeforces Beta Round #86 (Div. 1 Only) 10
208 Toys Codeforces School Team Contest #2 (Winter Computer School 2010/11) 10
209 Bingo! Codeforces MemSQL Start[c]UP 2.0 - Round 2 10
210 Drawing Circles is Fun Codeforces Codeforces Round #219 (Div. 1) 10
211 Vasily the Bear and Painting Square Codeforces Codeforces Round #195 (Div. 2) 10
212 Nephren Runs a Cinema Codeforces Codeforces Round #449 (Div. 1) 10
213 Shake It! Codeforces Codeforces Round #431 (Div. 1) 10
214 Numbers on the blackboard Codeforces Codeforces Round #443 (Div. 1) 10
215 Days of Floral Colours Codeforces Codeforces Round #431 (Div. 1) 10