Could you pass a storage array to the function? Like so:
function subsetsum(m::Int, n::Int, w::Array{Int,1}, x::Array{Bool,1},
s::Int, k::Int, r::Int, sol::Array{Bool,1})
local j::Int = 0
x[k] = true
if s + w[k] == m
push!(sol, w[find(x[1:k])])
else
if s + w[k] + w[k+1] <= m
subsetsum(m, n, w, x, s+w[k], k+1, r-w[k], sol)
end
end
if s + r - w[k] >= m && s + w[k+1] <= m
x[k] = false
subsetsum(m, n, w, x, s, k+1, r-w[k], sol)
end
end
> *The problem is*: Solutions found are printed to the console.
> Of course, I would like to store all solutions, for instance in a Boolean
> array of size k x n where k is the number of solutions.
> I managed to do this with a global array X but I assume this will make
> the algorithm considerably slower because
>
> 1. as I learned here, usage of globals slows Julia down
> 2. it is unknown how many solutions there are, so the array will have to
> grow
I think there are three approaches:
- do as you did/above
- if you have an idea of the number of solutions, use
`sizehint(sol, numsols)`. Or do sizehints in big junks.
- run the computation twice, once to compute the number of solutions,
the second time around to fill the `sol` array.
No idea which one is fastest.
