Combinatorics.jl
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JuliaMath
A combinatorics library for Julia
The following error may be averted, or such functionality made possible with an additional method: https://github.com/JuliaMath/Combinatorics.jl/blob/c2114a71ccfc93052efb9a9379e62b81b9388ef8/src/factorials.jl#L47-L54 An example of how `‼︎` can be extended to the signed integers is found...
We are missing https://en.wikipedia.org/wiki/Composition_(combinatorics) I think equivalent to `unique(permutations(partitions(n))` For the compositions with bounded terms the total number is given by Fibonacci sequences: https://math.stackexchange.com/questions/3055314/number-of-compositions-of-n-such-that-each-term-is-less-than-equal-to-k
If you change the type of the dict to `Dict{BigInt,BigInt}` in this line https://github.com/JuliaMath/Combinatorics.jl/blob/master/src/partitions.jl#L58 then `length(partitions(n))` returns correct results for larger values of `n`. The largest result that can be...
`multinomial` internally uses `binomial`. While the latter check for overflow, the whole computation of `multinomial` is not checked for overflow, leading to : `multinomial(150, 150, 150, 150)` --> error overflow...
powerset(::Set) works, but returns Iterator. ```julia julia> s Set{Char} with 3 elements: 'a' 'c' 'b' julia> collect(powerset(s)) ERROR: MethodError: no method matching getindex(::Set{Char}, ::Int64) ``` `collect(powerset(collect(s)))` works as expected though....
It might be worthwhile to combine the `combinations` and `with_replacement_combinations` functions. I could see a potential API as ```julia combinations(x, n) # No replacement combinations(x, n, replace=true) # With replacement...
`permutations()` seems slower than it should be. Below is the example I discovered this with. I have an array of strings, of length ~2,000. I would like to produce all...
`stirlings2` is implemented twice in this package. - [`stirlings2`](https://github.com/JuliaMath/Combinatorics.jl/blob/v1.0.0/src/numbers.jl#L154) is correct but recursive and slow. - [`nfixedsetpartitions`](https://github.com/JuliaMath/Combinatorics.jl/blob/v1.0.0/src/partitions.jl#L338) is bugged eg. it silently overflows. `stirlings2` is slow : ``` julia> @btime...
Delannoy is one of the most common function used in Competitive Programming, therefore typed a dynamically programmed function for the same.
This would close #79 #80 and #81. Solution is due to @simonschoelly. Note that `integer_partitions` is still implemented, but now just `collect`s `partitions(n::Int)`. However, this implementation now returns the partitions...
