Merge branch 'master' of github.com:JuliaLang/julia

examples/shootout/meteor-contest.jl

@@ -0,0 +1,250 @@
+# The Computer Language Benchmarks Game
+# http://shootout.alioth.debian.org/
+#
+# Contributed by David Campbell
+# based on Python version by Olof Kraigher
+
+const width  =  5
+const height = 10
+
+# directions
+const E  = 0
+const NE = 1
+const NW = 2
+const W  = 3
+const SW = 4
+const SE = 5
+
+const rotate = {E => NE, NE => NW, NW => W, W => SW, SW => SE, SE => E}
+const flip   = {E => W, NE => NW, NW => NE, W => E, SW => SE, SE => SW}
+
+const move = {
+    E  => (x, y) -> (x +   1,     y),
+    W  => (x, y) -> (x -   1,     y),
+    NE => (x, y) -> (x + y%2,     y - 1),
+    NW => (x, y) -> (x + y%2 - 1, y - 1),
+    SE => (x, y) -> (x + y%2,     y + 1),
+    SW => (x, y) -> (x + y%2 - 1, y + 1)
+}
+
+const pieces = (
+    (E,  E,  E,  SE),
+    (SE, SW, W,  SW),
+    (W,  W,  SW, SE),
+    (E,  E,  SW, SE),
+    (NW, W,  NW, SE, SW),
+    (E,  E,  NE, W),
+    (NW, NE, NE, W),
+    (NE, SE, E,  NE),
+    (SE, SE, E,  SE),
+    (E,  NW, NW, NW)
+)
+
+solutions = Any[]
+masks = zeros(Uint64, 10)
+masksAtCell = Array(Any, width*height, height)
+
+valid(x, y) = (0 <= x < width) && (0 <= y < height)
+legal(mask::Uint64, board::Uint64) = (mask & board) == 0
+zerocount(mask::Uint64) = sum([((uint64(1) << x) & mask) == 0 for x in 0:49])
+
+function findFreeCell(board::Uint64)
+    for y in 0:height-1
+        for x in 0:width-1
+            if board & (uint64(1) << (x + width*y)) == 0
+                return x, y
+            end
+        end
+    end
+end
+
+function floodFill(board::Uint64, fixme)
+    x, y = fixme
+    if !valid(x,y)
+        return board
+    end
+
+    if board & (uint64(1) << (x + width*y)) != 0
+        return board
+    end
+
+    board |= uint64(1) << (x + width*y)
+    for f in values(move)
+        board |= floodFill(board, f(x, y))
+    end
+
+    return board
+end
+
+function noIslands(mask::Uint64)
+    zeroes_ = zerocount(mask)
+
+    if zeroes_ < 5
+        return false
+    end
+
+    while mask != 0x3FFFFFFFFFFFF
+        mask = floodFill(mask, findFreeCell(mask))
+        new_zeroes = zerocount(mask)
+
+        if zeroes_ - new_zeroes < 5
+            return false
+        end
+
+        zeroes_ = new_zeroes
+    end
+
+    return true
+end
+
+function getBitmask(x, y, piece)
+    mask = (uint64(1) << (x + width*y))
+
+    for cell_ in piece
+        x, y = move[cell_](x,y)
+        if valid(x, y)
+            mask |= uint64(1) << (x + width*y)
+        else
+            return false, uint64(0)
+        end
+    end
+
+    return true, uint64(mask)
+end
+
+function allBitmasks(piece, color)
+    bitmasks = Uint64[]
+    for orientations in 0:1
+        for rotations in 0:(6 - 3*(color == 4)) - 1
+            for y in 0:height - 1
+                for x in 0:width - 1
+                    isValid, mask = getBitmask(x, y, piece)
+                    if isValid && noIslands(uint64(mask))
+                        push(bitmasks, mask)
+                    end
+                end
+            end
+            piece = [rotate[cell_] for cell_ in piece]
+        end
+        piece = [flip[cell_] for cell_ in piece]
+    end
+    return bitmasks
+end
+
+function generateBitmasks()
+    for i = 1:length(masksAtCell)
+        masksAtCell[i] = Uint64[]
+    end
+
+    color = 0
+    for piece in pieces
+        masks = allBitmasks(piece, color)
+        sort!(masks)
+        cellMask = uint64(1) << (width*height - 1)
+        cellCounter = width*height - 1
+
+        j = length(masks) - 1
+
+        while j >= 0
+            if (masks[j + 1] & cellMask) == cellMask
+                push(masksAtCell[cellCounter + 1, color + 1], masks[j + 1])
+                j -= 1
+            else
+                cellMask >>= 1
+                cellCounter -= 1
+            end
+        end
+        color += 1
+    end
+end
+
+function solveCell(cell_, board::Uint64, n)
+    if length(solutions) >= n
+        return
+    end
+
+    if board == 0x0003FFFFFFFFFFFF
+        # Solved
+        s = stringOfMasks(masks)
+        push(solutions, s)
+        push(solutions, reverse(s))
+        return
+    end
+
+    if board & (uint64(1) << cell_) != 0
+        # Cell full
+        solveCell(cell_ - 1, uint64(board), n)
+        return
+    end
+
+    if cell_ < 0
+        # Out of board
+        return
+    end
+
+    for color in 0:9
+        if masks[color + 1] == 0
+            for mask in masksAtCell[cell_ + 1, color + 1]
+                if legal(mask, board)
+                    masks[color + 1] = mask
+                    solveCell(cell_ - 1, uint64(board | mask), n)
+                    masks[color + 1] = 0
+                end
+            end
+        end
+    end
+end
+
+function solve(n)
+    generateBitmasks()
+    solveCell(width*height-1, uint64(0), n)
+end
+
+function stringOfMasks(masks)
+    s = ""
+    mask::Uint64 = 1
+    for y in 0:height - 1
+        for x in 0:width - 1
+            for color in 0:9
+                if (masks[color + 1] & mask) != 0
+                    s = strcat(s, color)
+                    break
+                elseif color == 9
+                    s += "."
+                end
+            end
+            mask <<= 1
+        end
+    end
+    return s
+end
+
+function printSolution(s)
+    for y in 0:height - 1
+        if y%2 == 1
+            print(" ")
+        end
+        for x in 0:width - 1
+            print("$(s[x + y*width + 1]) ")
+        end
+        println()
+    end
+end
+
+function main()
+    if length(ARGS) < 1
+        n = 2098
+    else
+        n = int(ARGS[1])
+    end
+
+    solve(n)
+    println("$(length(solutions)) solutions found")
+    println()
+    printSolution(min(solutions))
+    println()
+    printSolution(max(solutions))
+    println()
+end
+
+main()