Manuel Simon Hirsig
93 lines
1.9 KiB
Lua
93 lines
1.9 KiB
Lua
local private, public = {}, {}
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Aux.sort = public
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public.LT = {}
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public.EQ = {}
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public.GT = {}
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-- stable sorting
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function public.merge_sort(A, comp)
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local n = getn(A)
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local B = {}
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local width = 1
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while width <= n do
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for i=1, n, 2 * width do
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private.merge(A, i, min(i + width, n), min(i + 2 * width - 1, n), B, comp)
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end
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private.copy_array(B, A, n)
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width = 2 * width
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end
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end
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function private.merge(A, start1, start2, last, B, comp)
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local i1 = start1
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local i2 = start2
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for i=start1,last do
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if i1 < start2 and (i2 > last or comp(A[i1], A[i2]) == public.LT or comp(A[i1], A[i2]) == public.EQ) then
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B[i] = A[i1]
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i1 = i1 + 1
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else
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B[i] = A[i2]
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i2 = i2 + 1
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end
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end
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end
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function private.copy_array(A, B, n)
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for i=1,n do
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B[i] = A[i]
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end
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end
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function public.invert_order(ordering)
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if ordering == public.LT then
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return public.GT
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elseif ordering == public.GT then
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return public.LT
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else
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return public.EQ
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end
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end
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function public.compare(a, b, nil_ordering)
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nil_ordering = nil_ordering or public.EQ
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if not a and b then
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return nil_ordering
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elseif a and not b then
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return public.invert_order(nil_ordering)
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elseif not a and not b then
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return public.EQ
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elseif a < b then
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return public.LT
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elseif a > b then
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return public.GT
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else
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return public.EQ
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end
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end
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function public.compare_from_lt(lt)
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return function(a, b)
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if lt(a, b) then
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return public.LT
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elseif lt(b, a) then
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return public.GT
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else
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return public.EQ
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end
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end
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end
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function public.multi_lt(...)
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for i=1,arg.n-1,2 do
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if arg[i] ~= arg[i+1] then
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return arg[i] < arg[i+1]
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end
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end
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return false
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end |