All Questions
8
questions
2
votes
0
answers
73
views
Mastermind guessing
I'm reading this problem and I can understand how they got the output for the first four test cases. But the last one I can't really arrive at it. Is there some mathematical concept that I can apply ...
- 67
11
votes
0
answers
295
views
Minimal number of masks to safely meet all contacts during pandemic
This is a generalization of a variant of Doctor's Dilemma puzzle.
The general problem
Given an undirected connected graph $G$, one meeting is organized for each edge.
When two vertices meet each ...
- 12.5k
28
votes
1
answer
1k
views
Number of ways to stack LEGO bricks
One of the most surprising combinatorial formulas I know of counts the number of LEGO towers built from $n$ "$1 \times 2$" blocks subject to four rules:
The bricks lie in a single plane.
Each brick ...
- 5,072
7
votes
1
answer
145
views
An intriguing distance-like invariant
I recently came across the following property while setting up problems for a discrete mathematics course. It is not too hard to prove it by induction, but I am wondering whether there is more to it - ...
- 27.4k
2
votes
0
answers
158
views
Describing the sequence A224239.
I've been trying to describe mathematically the $n$th term $a_n$ of the sequence A224239. We get $a_n$ by counting the distinct ways to fill an $n\times n$ grid with squares of smaller integer size, ...
- 45.7k
3
votes
2
answers
339
views
Articles on matchstick puzzles
There are many ingenious puzzles involving matchsticks that are arranged as squares, rectangles or triangles, and can be moved under some restrictions (for a lot of examples see http://www.learning-...
user126526
4
votes
0
answers
133
views
How many Hamiltonian loop are there in a big rectangle?
Suppose I have some big rectangle made of $n \times m$ squares, and I want to place tiles on it in a manner that makes a picture of a hamiltonian loop.
I can transform this problem into a problem of ...
- 50.5k
10
votes
2
answers
701
views
"8 Dice arranged as a Cube" Face-Sum Equals 14 Problem
I found this here:
Sum Problem
Given eight dice. Build a $2\times 2\times2$ cube, so that the sum of the points on each side is the same.
$\hskip2.7in$
Here is one of 20 736 ...
- 18.6k