Combinatorics is a branch of mathematics concerning the study of finite or countable discrete structures.

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Summative Pattern

While playing around with J (link), I found that you can create a sequence of shape N0 N1 ... NK with i. taking a list as its ...
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56 views

3D Bin Packing using Java

This is a follow up question to 3D bin packing in Java ...
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2answers
61 views

all combinations of all sizes less than N

I want to generate all possible combinations (without duplicates) of all sizes less or equal than \$N\$, so for example if \$N=3\$ I want to generate the following \$\{1\},\{2\},\{3\}, ...
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1answer
57 views

Permutations with repetitions algorithm in R

Given a string of length n, print all permutation of the given string. The code bellow generates all permutations (with repetitions) for the given string and stores them in object ...
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1answer
81 views
2
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1answer
47 views

3D bin packing in Java

I made some changes to the first code here I wrote and I want to know which one is more correct logically (before the changes or after the changes). It's really hard to manually test these kind of ...
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1answer
47 views

3D bin packing algorithm using Java?

I wrote a 3D bin packing algorithm but I am still not sure if it is correct or not. I did not follow any code or pseudo-code that's why I would like to know if it is an efficient algorithm for the 3D ...
9
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2answers
108 views

Finding all contiguous sublists such that each member appears an even number of times

The program needs to find all contiguous sublists of numbers where the number of occurrences of every member in the contiguous sublist is divisible by 2. The first line of input is N (the number of ...
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2answers
155 views

Java 8 Stream to produce all permutations of an array using recursion

I want to write a class that returns a Stream of permutations of an int[]. ...
9
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5answers
241 views

Pizza Hut math problem #1 in Haskell

I'm currently attempting to learn Haskell after a fair history of imperative programming. When I saw the Pizza Hut Pi Day math problems, I thought the first one would be a good candidate for my ...
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1answer
52 views
1
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1answer
51 views

Finding Kth Permutation Sequence

I have written a program to display the kth permutation sequence of a string made up of letters 'O' and 'Z' . I tried optimizing it but my code have not passed test cases due to timeout issues.Looking ...
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1answer
94 views

Characters set permutations with repetitions

The code bellow generates all the permutation(with repetitions) for given character set. Is there any better(simpler, more performant) way to do that? ...
5
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1answer
99 views

Finding ways to achieve a target sum using recursion

I need your review and suggestions how to make this code better. I'm just learning recursion and sure that this solution is not ideal. Question: Write a function that given an input array of ...
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3answers
72 views

Korean word segmentation using frequency heuristic

This a continuation of a previous question. I want to thank Joe Wallis for his help with increasing the readability of my code. Although the changes made by Joe Wallis did increase the speed of the ...
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1answer
95 views

Round Robin Tournament

RoundRobin is an implementation of the Round-robin style tournament: ...
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2answers
53 views

Making the same amount from different combinations of coins (top-down approach)

I was reading a typical interview question found here. Given an amount and a list of denominations, count the number of possible ...
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1answer
64 views

Improving Speeds of Tokenisation of large word list for distinct combinations

I'm having trouble with a current algorithm I'm writing that takes a corpa, a list of characters in sets (1 one or larger) with a frequency number attached to it. Against another list of character ...
6
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1answer
54 views

All possible ways of merging two lists while keeping their order

I am writing a function gives all possible ways of merging two ordered lists such that in the merged list, the elements are still ordered according to the elements in their respective starting list. ...
6
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2answers
91 views

An iterator returning all possible partitions of a list in Java

Given a list of \$n\$ objects and an integer \$k \in \{ 1, 2, \dots, n \}\$, this iterator generates all possible ways of partitioning the elements in the list into exactly \$k\$ disjoint, non-empty ...
5
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0answers
107 views

An iterator returning all possible permutations of a list in Java

I have this class that iterates over all permutations of an input list: PermutationIterable.java: ...
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0answers
54 views

Generate Subsets Of K Elements From A Set Of Strings

This is the task: Write a recursive program, which prints all subsets of a given set of N words. Example input: words = {'test', 'rock', 'fun'} ...
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2answers
87 views

Combination generator in Java - 2nd iteration

I have refactored the previous combination generator, and now it is an iterator returning combinations as lists. It hides larger constant factors as the previous version, yet it is really easy to use: ...
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2answers
34 views

multirange iterator

I'm doing some boring math with lot of sums over lot of variables. So, instead of nesting for loops I have decided to use something like this: ...
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5answers
794 views

Generate a dictionary of passwords

I have a Python script that generates a dictionary of all possible 3 digit password combinations. It essentially works by just nesting for loops. This is fine, but ...
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450 views

Solution to King Kohima problem in Python

King Kohima problem: King Kohima has reserved a new exclusive street for his executive class employees where they can build their homes. He has assigned you to plan that street. You have to ...
4
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1answer
96 views

Combination generator in Java

(See the next iteration.) Given a positive \$N\$, the following class generates all possible non-empty sets \$A \in \mathcal{P}(\{0, 1, \dots, N - 1\})\$ in lexicographic order. Also, it provides a ...
8
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1answer
85 views

Scala implementation of @rolfl's integer-partitioning algorithm

While reviewing @Martijn's Distinct sums of integers (finding all combinations of positive integers that sum to a given number), I proposed the following solution: ...
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2answers
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C permutation generator

I am making a permutation generator in c. Any ideas how I can make it faster? ...
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3answers
84 views

Searching a string for any permutation of words

Given a string and an array of words, return all indexes in string for which a concatenation of all words in the array, in any order (so ["eensie", "weensy", "spider"] has six orderings) can be ...
7
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1answer
94 views

Recursive program for generating and printing all permutations of the numbers 1, 2, …, n for given integer number n

I've just written code for generating all permutations of the numbers from 1 to n in Java. It seems to work, but I think it's a bit more complex than it needs to be. ...
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1answer
99 views

Permutation function in C#

One thing lead to another and eventually I wanted to know the "proper" way of writing the permutation generating function in C#. Below is my code for generating permutations. This will go into an ...
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5answers
565 views

isPermutation method

I wrote an isPermute method. Can I get some tips and advice on better coding style? ...
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4answers
933 views

Printing all possible sums of two n-sided dice rolls

For my CS class, we were tasked with writing a program that calculates all the possible results from rolling two n-sided dice. For example, the input of 4 would ...
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3answers
61 views

Finding tuples of numbers subject to constraints

I just watched the video from "Think Like a Programmer, Episode 2: Puzzles & Problems". The problem is: Assign number 1-7 to three departments in a city: Fire, Police, Sanitation. ...
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1answer
143 views

Finding permutations of a word

This was a basic anagram problem. Take an input word, find all its permutations, then check a dictionary file to see what if any of those are real words. Dictionary file My input data: ...
11
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1answer
134 views

Counting paths in an n-dimensional grid that stay within the boundaries

Problem Statement You are situated in an N dimensional grid at position (x1, x2, …, xN). The dimensions of the grid are (D1, D2, …, DN). In one step, you can walk one step ahead or behind in ...
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1answer
246 views

Programming Challenge from Kattis: Apparatus

I am trying to solve apparatus problem, paraphrased below. There is an apparatus with n on/off switches with a one-to-one correspondence to n lights (but with an unknown permutation). We have ...
8
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0answers
109 views

Permuting a typelist

Given a typelist, return a typelist of all the permutations of it. For example: ...
3
votes
1answer
64 views

`r` permutations of `n`

I have written this snippet to find r-permutations of n, i.e. if I have an array of n=3 {0,1,2}, then r=2 permutations will be {{0, 1}, {0, 2}, {1, 0}, {1, 2}, {2, 0}, {2, 1}}. Can somebody review it ...
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2answers
118 views

Generate all combinations of certain digits

Related to another answer of mine on Project Euler 35, I found the need to calculate all combinations of certain digits, i.e. 1, 3, 7 and 9, below a given n. I ...
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votes
2answers
56 views

Find unique variants of a product

I am writing a piece of code that returns all the unique variants that a product is available in for an ecommerce app. For example, a shirt product can be available in different colors, sizes, and ...
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1answer
29 views

Coins problem in Erlang

How many different ways can 200 be made using any number of coins? The possible denominations are 1, 2, 5, 10, 20, 50, 100, 200. ...
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2answers
107 views
17
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2answers
278 views

Calculate all possible distributions of n objects to k containers

Let's say I have \$5\$ apples, thus \$n = 5\$. I have three bags (\$k = 3\$), each having the capacities of \$4\$, \$4\$ and \$2\$: $$c = { \{4, 4, 2 \}}$$ I'd like to calculate the number of ways ...
4
votes
1answer
160 views

Counting ways to fit bottles in crates

I'm calculating how many possibilities there are to fit \$n\$ identical bottles inside \$k\$ crates of various capacities. n = Number of bottles k = Number of crates K = List of the number of ...
2
votes
2answers
178 views

Non-Contiguous Substrings

Problem: A non-contiguous substring of string \$s\$ is a sequence of \$k \geq 0\$ characters in \$s\$, in the order in which they occur in \$s\$. For instance, the set of all non-contiguous ...
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3answers
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Find co-occurrence of elements

My input consists of a list of lists (not necessary of the same length), like ...
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2answers
292 views

Generating 3 combinations in Python

I have been experimenting around with generating all the n-combinations of an array. This code quickly generates all \$\text{k-combinations}\$ of a given array. I am testing my own implementation ...