Questions tagged [combinatorics]
For challenges involving combinatorics.
393 questions
-7 votes
0 answers
137 views
Buscar (a,b,c) que cumpla a!*b! /c! = 1 [closed]
Find all triples (a,b,c) that satisfy (a! * b!) / c! = 1 The following non-trivial combinations were found in the first 50 numbers: (3! * 5!) / 6! = 1 (4! * 23!) / 24! = 1 (6! * 7!) / 10! = 1 In ...
9 votes
1 answer
375 views
Ruler-and-compass constructions
In this code-golf challenge, you will work with a construction that was used by the ancient Greeks: the straightedge-and-compass construction. In particular, you will count how many different ...
- 8,155
16 votes
17 answers
1k views
Counting Gessel walks
OEIS A135404 gives the number of Gessel walks \$g(n)\$ of length \$2n\$. A Gessel walk is a walk on the square lattice starting and ending at the origin with possible steps (1,0), (-1,0), (1,1), (-1,-...
- 4,749
7 votes
9 answers
1k views
Card-Jitsu Part 1: Find all winning sets of three cards
Part 2 is available here Card-Jitsu was a mini card-game based on Rock, Paper, Scissors available on the children MMO game Club Penguin. I first wrote a challenge where you needed to implement a clone ...
- 937
15 votes
9 answers
1k views
How many chains?
Given a positive integer \$n\$, a partition of \$n\$ is an ascending sequence of numbers that sum to \$n\$. Given two partitions \$a\$ and \$b\$, \$a\$ is a refinement of \$b\$ iff \$b\$ can be ...
- 103k
14 votes
11 answers
1k views
Counting Rota-Baxter words
A Rota-Baxter word, \$w\$, is a string made of the symbols a, (, and ) such that the ...
- 103k
2 votes
11 answers
823 views
Climbing through the mountains on all paths
Narrative We are standing at the foot of a mountain. To find the best route when climbing the mountain, let's consider all possible routes. On our route, there is no point lower than our starting ...
- 1,742
15 votes
10 answers
2k views
Walks in Nice (Nizza)
Narrative Recently, I visited Nice (a French city on the Mediterranean coast) and saw a curious tourist wandering through the city. His walk started at the center of the 'Promenade des Anglais'. He ...
- 1,742