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109 lines
3.8 KiB
Plaintext
109 lines
3.8 KiB
Plaintext
/*
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* Copyright (c) 2013-2014 Galois, Inc.
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* Distributed under the terms of the BSD3 license (see LICENSE file)
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*/
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// The classic "marble jumping" puzzle
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// see: http://en.wikipedia.org/wiki/Peg_solitaire
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// this is the "European" variation
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type Board = [7][7]Bit
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all : {n} (fin n) => [n] -> Bit
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all xs = xs == ~zero
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popCount : {a,b} (fin a, b >= 1, b == (lg2 a)) => [a] -> [b]
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popCount bs = ic ! 0 where
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ic = [0] # [ if elt then prev + 1 else prev | elt <- bs | prev <- ic]
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posns : Board
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posns = [[False,False,True,True,True,False,False],
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[False,True,True,True,True,True,False],
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[True,True,True,True,True,True,True],
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[True,True,True,True,True,True,True],
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[True,True,True,True,True,True,True],
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[False,True,True,True,True,True,False],
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[False,False,True,True,True,False,False]]
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start : Board
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start = [[False,False,True,True,True,False,False],
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[False,True,True,True,True,True,False],
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[True,True,True,True,True,True,True],
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[True,True,True,False,True,True,True],
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[True,True,True,True,True,True,True],
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[False,True,True,True,True,True,False],
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[False,False,True,True,True,False,False]]
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// testing positions
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first : Board
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first = [[False,False,True,True,True,False,False],
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[False,True,True,True,True,True,False],
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[True,True,True,True,True,True,True],
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[True,True,True,True,False,False,True],
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[True,True,True,True,True,True,True],
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[False,True,True,True,True,True,False],
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[False,False,True,True,True,False,False]]
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second : Board
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second = [[False,False,True,True,True,False,False],
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[False,True,True,True,True,True,False],
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[True,True,True,True,True,True,True],
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[True,True,True,True,True,False,True],
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[True,True,True,True,False,True,True],
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[False,True,True,True,False,True,False],
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[False,False,True,True,True,False,False]]
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goal : Board
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goal = [[False,False,False,False,False,False,False],
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[False,False,False,True,False,False,False],
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[False,False,False,False,False,False,False],
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[False,False,False,False,False,False,False],
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[False,False,False,False,False,False,False],
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[False,False,False,False,False,False,False],
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[False,False,False,False,False,False,False]]
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validBoard : Board -> Bit
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validBoard b = join (b && ~posns) == zero
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validRowJump : Board -> Board -> Bit
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validRowJump a a' = validBoard a
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&& validBoard a'
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&& validRowMove (differentRow a a')
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differentRow : Board -> Board -> ([7], [7])
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differentRow a a' = rows ! 0
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where rows = [(0b0000000,0b0000000)]
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# [ if row != row' then (row,row') else old
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| row <- a
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| row' <- a'
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| old <- rows ]
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validRowMove : ([7], [7]) -> Bit
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validRowMove (r, r') = (xors == 0b0000111 ||
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xors == 0b0001110 ||
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xors == 0b0011100 ||
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xors == 0b0111000 ||
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xors == 0b1110000)
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&& (
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rxors == 0b0000011 ||
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rxors == 0b0000110 ||
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rxors == 0b0001100 ||
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rxors == 0b0011000 ||
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rxors == 0b0110000 ||
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rxors == 0b1100000)
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where xors = r ^ r'
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rxors = r && rxors
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validColJump : Board -> Board -> Bit
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validColJump a a' = validRowJump (transpose a) (transpose a')
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validMove : Board -> Board -> Bit
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validMove a a' = validRowJump a a' || validColJump a a'
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validMoveSequence : {n} (fin n, n >= 1) => [n] Board -> Bit
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validMoveSequence moves = all [validMove a b | a <- moves | b <- drop`{1} moves]
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solutionInNmoves : {n} (fin n) => [n] Board -> Bit
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property solutionInNmoves ms = validMoveSequence ([start] # ms # [second])
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