41 lines
1008 B
Standard ML
41 lines
1008 B
Standard ML
structure BinSearch =
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struct
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fun helpExists (findNum, vec, low, high) =
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if high >= low then
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let
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val mid = low + ((high - low) div 2)
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val curNum = Vector.sub (vec, mid)
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in
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if curNum = findNum then
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true
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else if curNum < findNum then
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helpExists (findNum, vec, mid + 1, high)
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else
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helpExists (findNum, vec, low, mid - 1)
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end
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else
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false
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fun exists (findNum, vec) =
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helpExists (findNum, vec, 0, Vector.length vec - 1)
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fun helpFind (findNum, vec, low, high) =
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if high >= low then
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let
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val mid = low + ((high - low) div 2)
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val curNum = Vector.sub (vec, mid)
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in
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if curNum = findNum then
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mid
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else if curNum < findNum then
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helpFind (findNum, vec, mid + 1, high)
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else
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helpFind (findNum, vec, low, mid - 1)
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end
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else
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~1
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fun find (findNum, vec) =
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helpFind (findNum, vec, 0, Vector.length vec - 1)
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end
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