105 lines
8.4 KiB
HTML
105 lines
8.4 KiB
HTML
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</head><body style="background-color:#232629;color:#cfcfc2"><pre>
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<span style="color:#7a7c7d">-- Test file for Kate's Euphoria syntax highlighting/code folding.</span>
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<span style="color:#2980b9;background-color:#153042">-- BEGIN region marker test</span>
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<span style="color:#7a7c7d">-- code here</span>
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<span style="color:#2980b9;background-color:#153042">-- END region marker test</span>
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<span style="color:#7a7c7d">-- The N Queens Problem:</span>
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<span style="color:#7a7c7d">-- Place N Queens on an NxN chess board</span>
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<span style="color:#7a7c7d">-- such that they don't threaten each other.</span>
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<span style="color:#2980b9">constant</span> N = <span style="color:#f67400">8</span> <span style="color:#7a7c7d">-- try some other sizes</span>
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<span style="color:#2980b9">constant</span> ROW = <span style="color:#f67400">1</span>, COLUMN = <span style="color:#f67400">2</span>
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<span style="color:#2980b9">constant</span> <span style="font-weight:bold">TRUE</span> = <span style="color:#f67400">1</span>, <span style="font-weight:bold">FALSE</span> = <span style="color:#f67400">0</span>
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<span style="font-weight:bold">type</span> square(<span style="color:#2980b9">sequence</span> x)
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<span style="color:#7a7c7d">-- a square on the board</span>
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<span style="font-weight:bold">return</span> <span style="font-weight:bold">length</span>(x) = <span style="color:#f67400">2</span>
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<span style="font-weight:bold">end type</span>
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<span style="font-weight:bold">type</span> row(<span style="color:#2980b9">integer</span> x)
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<span style="color:#7a7c7d">-- a row on the board</span>
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<span style="font-weight:bold">return</span> x >= <span style="color:#f67400">1</span> <span style="font-weight:bold">and</span> x <= N
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<span style="font-weight:bold">end type</span>
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<span style="font-weight:bold">function</span> threat(square q1, square q2)
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<span style="color:#7a7c7d">-- do two queens threaten each other?</span>
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<span style="font-weight:bold">if</span> q1[COLUMN] = q2[COLUMN] <span style="font-weight:bold">then</span>
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<span style="font-weight:bold">return</span> <span style="font-weight:bold">TRUE</span>
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<span style="font-weight:bold">elsif</span> q1[ROW] - q1[COLUMN] = q2[ROW] - q2[COLUMN] <span style="font-weight:bold">then</span>
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<span style="font-weight:bold">return</span> <span style="font-weight:bold">TRUE</span>
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<span style="font-weight:bold">elsif</span> q1[ROW] + q1[COLUMN] = q2[ROW] + q2[COLUMN] <span style="font-weight:bold">then</span>
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<span style="font-weight:bold">return</span> <span style="font-weight:bold">TRUE</span>
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<span style="font-weight:bold">elsif</span> q1[ROW] = q2[ROW] <span style="font-weight:bold">then</span>
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<span style="font-weight:bold">return</span> <span style="font-weight:bold">TRUE</span>
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<span style="font-weight:bold">else</span>
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<span style="font-weight:bold">return</span> <span style="font-weight:bold">FALSE</span>
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<span style="font-weight:bold">end if</span>
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<span style="font-weight:bold">end function</span>
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<span style="font-weight:bold">function</span> conflict(square q, <span style="color:#2980b9">sequence</span> queens)
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<span style="color:#7a7c7d">-- Would square p cause a conflict with other queens on board so far?</span>
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<span style="font-weight:bold">for</span> i = <span style="color:#f67400">1</span> <span style="font-weight:bold">to</span> <span style="font-weight:bold">length</span>(queens) <span style="font-weight:bold">do</span>
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<span style="font-weight:bold">if</span> threat(q, queens[i]) <span style="font-weight:bold">then</span>
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<span style="font-weight:bold">return</span> <span style="font-weight:bold">TRUE</span>
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<span style="font-weight:bold">end if</span>
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<span style="font-weight:bold">end for</span>
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<span style="font-weight:bold">return</span> <span style="font-weight:bold">FALSE</span>
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<span style="font-weight:bold">end function</span>
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<span style="color:#2980b9">integer</span> soln
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soln = <span style="color:#f67400">0</span> <span style="color:#7a7c7d">-- solution number</span>
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<span style="font-weight:bold">procedure</span> print_board(<span style="color:#2980b9">sequence</span> queens)
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<span style="color:#7a7c7d">-- print a solution, showing the Queens on the board</span>
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<span style="color:#2980b9">integer</span> k
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<span style="font-weight:bold">position</span>(<span style="color:#f67400">1</span>, <span style="color:#f67400">1</span>)
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<span style="font-weight:bold">printf</span>(<span style="color:#f67400">1</span>, <span style="color:#f44f4f">"Solution #%d\n\n "</span>, soln)
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<span style="font-weight:bold">for</span> c = 'a' <span style="font-weight:bold">to</span> 'a' + N - <span style="color:#f67400">1</span> <span style="font-weight:bold">do</span>
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<span style="font-weight:bold">printf</span>(<span style="color:#f67400">1</span>, <span style="color:#f44f4f">"%2s"</span>, c)
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<span style="font-weight:bold">end for</span>
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<span style="font-weight:bold">puts</span>(<span style="color:#f67400">1</span>, <span style="color:#f44f4f">"\n"</span>)
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<span style="font-weight:bold">for</span> r = <span style="color:#f67400">1</span> <span style="font-weight:bold">to</span> N <span style="font-weight:bold">do</span>
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<span style="font-weight:bold">printf</span>(<span style="color:#f67400">1</span>, <span style="color:#f44f4f">"%2d "</span>, r)
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<span style="font-weight:bold">for</span> c = <span style="color:#f67400">1</span> <span style="font-weight:bold">to</span> N <span style="font-weight:bold">do</span>
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<span style="font-weight:bold">if</span> <span style="font-weight:bold">find</span>({r,c}, queens) <span style="font-weight:bold">then</span>
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<span style="font-weight:bold">puts</span>(<span style="color:#f67400">1</span>, <span style="color:#f44f4f">"Q "</span>)
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<span style="font-weight:bold">else</span>
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<span style="font-weight:bold">puts</span>(<span style="color:#f67400">1</span>, <span style="color:#f44f4f">". "</span>)
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<span style="font-weight:bold">end if</span>
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<span style="font-weight:bold">end for</span>
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<span style="font-weight:bold">puts</span>(<span style="color:#f67400">1</span>, <span style="color:#f44f4f">"\n"</span>)
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<span style="font-weight:bold">end for</span>
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<span style="font-weight:bold">puts</span>(<span style="color:#f67400">1</span>, <span style="color:#f44f4f">"\nPress Enter. (q to quit) "</span>)
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<span style="font-weight:bold">while</span> <span style="font-weight:bold">TRUE</span> <span style="font-weight:bold">do</span>
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k = <span style="font-weight:bold">get_key</span>()
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<span style="font-weight:bold">if</span> k = 'q' <span style="font-weight:bold">then</span>
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<span style="font-weight:bold">abort</span>(<span style="color:#f67400">0</span>)
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<span style="font-weight:bold">elsif</span> k != -<span style="color:#f67400">1</span> <span style="font-weight:bold">then</span>
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<span style="font-weight:bold">exit</span>
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<span style="font-weight:bold">end if</span>
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<span style="font-weight:bold">end while</span>
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<span style="font-weight:bold">end procedure</span>
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<span style="font-weight:bold">procedure</span> place_queen(<span style="color:#2980b9">sequence</span> queens)
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<span style="color:#7a7c7d">-- place queens on a NxN chess board</span>
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<span style="color:#7a7c7d">-- (recursive procedure)</span>
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row r <span style="color:#7a7c7d">-- only need to consider one row for each queen</span>
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<span style="font-weight:bold">if</span> <span style="font-weight:bold">length</span>(queens) = N <span style="font-weight:bold">then</span>
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soln += <span style="color:#f67400">1</span>
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print_board(queens)
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<span style="font-weight:bold">return</span>
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<span style="font-weight:bold">end if</span>
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r = <span style="font-weight:bold">length</span>(queens)+<span style="color:#f67400">1</span>
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<span style="font-weight:bold">for</span> c = <span style="color:#f67400">1</span> <span style="font-weight:bold">to</span> N <span style="font-weight:bold">do</span>
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<span style="font-weight:bold">if</span> <span style="font-weight:bold">not</span> conflict({r,c}, queens) <span style="font-weight:bold">then</span>
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place_queen(<span style="font-weight:bold">append</span>(queens, {r,c}))
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<span style="font-weight:bold">end if</span>
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<span style="font-weight:bold">end for</span>
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<span style="font-weight:bold">end procedure</span>
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</pre></body></html>
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