All Questions
Tagged with algorithm combinatorics
133 questions
2
votes
0
answers
21
views
Mathematica implementation of Welch method for constructing Costas arrays
I ported C++ implementation of Welch method for constructing Costas arrays to Mathematica.
Any feedback would be appreciated.
...
- 453
3
votes
1
answer
90
views
<Programming in Lua - 4th> exercise 2.2 - place 8 queens
About exercise 2.2
Place N queens on N*N board, 1 queen per line, so that all queens are safe.
Use permutation to improve the provided implementation from book.
The ...
- 151
3
votes
2
answers
211
views
Find the join of two set partitions
Two partitions of a set have a greatest lower bound (meet) and a least upper bound (join).
See here: Meets and joins in the lattice of partitions (Math SE)
The meet is easy to calculate. I am trying ...
- 230
3
votes
1
answer
90
views
Number of partitions of (a,b) into k distinct parts which sum up to (a,b)
Problem set
This is somewhat a generalization of the famous partition of integer n into k parts.
Given two integers ...
0
votes
0
answers
114
views
Generating group permutations: an extended Heap's algorithm in Java
Suppose we have a sequence of sequences <1, 2> <3, 4>. There, we have two groups: <1, 2> and ...
- 31k
3
votes
1
answer
163
views
String Permutation Implemention
The objective is simple: List all possible permutations for a given a String. I looked at some implementations from popular sources. I decided to build this to the flow:
The Code for Review
...
1
vote
1
answer
228
views
Creates all possible permutations of a string and its substrings
I want to improve this code to efficiently create all possible permutations/combinations of a string. For example, if I have the string "abc", the result would be the list [ab, ac, ba, bc, ...
- 11
7
votes
2
answers
1k
views
Find all combinations of length 3 whose sum is divisible by a given number
I came up with a suitable solution to a HackerRank problem that failed because the execution took longer than 10 seconds on lists that were of very large size.
The problem: Given a list ...
2
votes
0
answers
124
views
Iterating over all simple unique cycles in an undirected graph in Java - brute-force approach
This post is about an Iterator iterating over simple loops of an undirected graph.
In the above graph, the cycle \$\langle 1, 2, 3, 4, 5, 3, 1 \rangle\$ is not ...
- 31k
1
vote
1
answer
90
views
An algorithm that minimizes the number of ingredients necessary
I am working on a code that will minimize the number of ingredients necessary to make some dishes.
Each dish can be prepared in an arbitrary large number of ways, with combinations of two ingredients. ...
- 485
2
votes
2
answers
804
views
Subarrays with length
You are given an array A of length N (where N is as large as 2×105). All elements of the array are positive integers less than or equal to N. Determine the count of subarrays (contiguous subsequences) ...
1
vote
1
answer
133
views
Subset Product Algorithm
Subset Product is an NP-complete problem and is my favorite problem. So, I've written a slightly smarter way of solving the problem.
Will performance impact matter if I use multi-cpus and my GPU?
Do ...
- 491
5
votes
2
answers
2k
views
Find non-overlapping pairs of elements in a list whose difference is less than some given threshold
I have the following task: Let us have a list (denoted by L, and for simplicity, the elements come from the interval [0,1]). We are given a parameter (denoted by C), and we want to find as many pairs ...
- 153
2
votes
1
answer
252
views
In how many different ways can a group of 9 people be divided into 3 groups, with each group containing 3 people?
To divide 9 persons into 3 groups, when the ordering of groups is not important can be done in
(9C3 * 6C3 * 3C3) / (3!) = 280 ways
Here, we divide by (3!) because the ordering of 3 groups is not ...
- 123
3
votes
1
answer
111
views
Building a tree containing all permutations of arithmetic expressions given some numbers
Given any series of numbers, for example 1,2,3,4,5 and given the arithmetic operands + - * / including parenthesis, what would be the most optimal way to build a tree that contains all permutations ...
- 133