Non-continuous subsequences: Difference between revisions

 

=={{header|Julia}}==

This solution uses an iterator over non-contiguous sub-sequences, <tt>NCSubSeq</tt>. In the spirit of Julia's <tt>permutations</tt> and <tt>combinations</tt> built-ins, <tt>NCSubSeq</tt> provides an array of indices that can be used to create each subsequence from the full sequence. Sub-sequences are indexed by integers whose bit patterns indicate which members are included.

 

 

'''Iterator and Functions'''

 

iscontseq(n::Integer) = count_zeros(n) == leading_zeros(n) + trailing_zeros(n)

iscontseq(n::BigInt) = !ismatch(r"0", rstrip(bin(n), '0'))

function makeint2seq(n::Integer)

function int2seq(m::Integer)

idex[d .== 1]

end

return int2seq

end

struct NCSubSeq{T<:Integer}

n::T

end

mutable struct NCSubState{T<:Integer}

m::T

m2s::Function

end

Base.length(a::NCSubSeq) = 2 ^ a.n - a.n * (a.n + 1) ÷ 2 - 1

s = as.m2s(as.m)

as.m += 1

return (s, as)

end

n = 4

println("Testing NCSubSeq for ", n, " items:\n ", join(NCSubSeq(n), " "))

s = "Rosetta"

cs = split(s, "")

m = 10

println("\nThe first and last ", m, " NC sub-sequences of \"", s, "\":")

i <= m || n < i || continue

println(@sprintf "%6d %s" i join(cs[a], ""))

println(" .. ......")

end

 

println("\nThe first and last ", m, " NC sub-sequences of \"", s, "\"")

@printf "%7d → %d\n" x length(NCSubSeq(x))

[1, 3] [1, 4] [2, 4] [1, 2, 4] [1, 3, 4]

 

100 → 1267650600228229401496703200325

150 → 1427247692705959881058285969449495136382735298

 

=={{header|Kotlin}}==