38 lines
872 B
Plaintext
38 lines
872 B
Plaintext
main =>
|
|
L = [9,8,7,6,5,0,1,2,3,4],
|
|
Len = L.len,
|
|
println([select(L,1,Len,I) : I in 1..Len]),
|
|
nl.
|
|
|
|
select(List, Left, Right, K) = Select =>
|
|
if Left = Right then
|
|
Select = List[Left]
|
|
else
|
|
PivotIndex = partition(List, Left, Right, random(Left,Right)),
|
|
if K == PivotIndex then
|
|
Select = List[K]
|
|
elseif K < PivotIndex then
|
|
Select = select(List, Left, PivotIndex-1, K)
|
|
else
|
|
Select = select(List, PivotIndex+1, Right, K)
|
|
end
|
|
end.
|
|
|
|
partition(List, Left, Right, PivotIndex) = StoreIndex =>
|
|
PivotValue = List[PivotIndex],
|
|
swap(List,PivotIndex,Right),
|
|
StoreIndex = Left,
|
|
foreach(I in Left..Right-1)
|
|
if List[I] @< PivotValue then
|
|
swap(List,StoreIndex,I),
|
|
StoreIndex := StoreIndex+1
|
|
end
|
|
end,
|
|
swap(List,Right,StoreIndex).
|
|
|
|
% swap L[I] <=> L[J]
|
|
swap(L,I,J) =>
|
|
T = L[I],
|
|
L[I] := L[J],
|
|
L[J] := T.
|