RosettaCodeData/Task/Range-extraction/Picat/range-extraction.picat

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go =>
Lists = [
[-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9,
10, 11, 14, 15, 17, 18, 19, 20],
[ 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17,
18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31,
32, 33, 35, 36, 37, 38, 39],
1..20,
[13],
[11,12,13,15]
].
foreach(List in Lists)
println(List),
println(make_ranges(List)),
nl
end,
nl.
make_ranges(L) = Res =>
Ranges = [],
Range = [L[1]],
% Identify the range
foreach(I in 2..L.length)
Li1 = L[I-1],
Li = L[I],
if Li == Li1+1 then
Range := Range ++ [Li]
else
if length(Range) > 0 then
Ranges := Ranges ++ [Range]
end,
Range := [] ++ [Li]
end
end,
% pickup the last range
if length(Range) > 0 then
Ranges := Ranges ++ [Range]
end,
Res := join([get_range(R) : R in Ranges], ",").
% Convert to range representation
get_range(R) =
cond(R.length == 1,
R.first().to_string(),
min(R).to_string() ++ "-" ++ max(R).to_string()).