Also, a brute-force (but simple-looking) approach that is O(n²) might be
function levicivita{T<:Integer}(p::AbstractVector{T})
n = lenght(p)
ɛ = 1
for i = 1:n
for j = i+1:n
ɛ *= sign(p[j] - p[i])
ɛ == 0 && return 0
end
end
return ɛ
end
