315 lines
8.6 KiB
C++
315 lines
8.6 KiB
C++
/* $NetBSD: algor.cc,v 1.2 2005/08/09 02:38:32 christos Exp $ */
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/*-
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* Copyright (c) 2003 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Christos Zoulas.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* algor.C: Computer algorithm
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*/
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#include "defs.h"
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RCSID("$NetBSD: algor.cc,v 1.2 2005/08/09 02:38:32 christos Exp $")
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#include "algor.h"
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#include "board.h"
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#include "box.h"
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#include "random.h"
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ALGOR::ALGOR(const char c) : PLAYER(c)
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{
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#ifdef notyet
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// Single Edges = (x + y) * 2
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_edge1 = (_b.nx() * _b.ny()) * 2;
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// Shared Edges = (x * (y - 1)) + ((x - 1) * y)
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_edge2 = (_b.nx() * (_b.ny() - 1)) + ((_b.nx() - 1) * _b.ny());
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// Maximum Edges filled before closure = x * y * 2
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_maxedge = _b.nx() * _b.ny() * 2;
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#endif
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}
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// Find the first closure, i.e. a box that has 3 edges
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int ALGOR::find_closure(size_t& y, size_t& x, int& dir, BOARD& b)
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{
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RANDOM rdy(b.ny()), rdx(b.nx());
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for (y = rdy(); y < b.ny(); y = rdy()) {
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rdx.clear();
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for (x = rdx(); x < b.nx(); x = rdx()) {
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BOX box(y, x, b);
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if (box.count() == 3) {
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for (dir = BOX::first; dir < BOX::last; dir++)
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if (!box.isset(dir))
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return 1;
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b.abort("find_closure: 3 sided box[%d,%d] has no free sides",
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y, x);
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}
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}
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}
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return 0;
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}
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#if 0
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size_t ALGOR::find_single()
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{
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size_t ne;
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// Find the number of single edges in use
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for (size_t x = 0; x < b.nx(); x++) {
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BOX tbox(0, x, b);
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ne += tbox.isset(BOX::top);
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BOX bbox(b.ny() - 1, x, b);
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ne += bbox.isset(BOX::bottom);
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}
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for (size_t y = 0; y < _b.ny(); y++) {
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BOX lbox(y, 0, b);
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ne += lbox.isset(BOX::left);
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BOX rbox(y,_b.nx() - 1, b);
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ne += rbox.isset(BOX::right);
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}
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return ne;
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}
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#endif
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// Count a closure, by counting all boxes that we can close in the current
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// move
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size_t ALGOR::count_closure(size_t& y, size_t& x, int& dir, BOARD& b)
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{
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size_t i = 0;
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size_t tx, ty;
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int tdir, mv;
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while (find_closure(ty, tx, tdir, b)) {
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if (i == 0) {
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// Mark the beginning of the closure
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x = tx;
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y = ty;
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dir = tdir;
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}
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if ((mv = b.domove(ty, tx, tdir, getWho())) == -1)
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b.abort("count_closure: Invalid move (%d, %d, %d)", y, x, dir);
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else
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i += mv;
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}
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return i;
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}
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/*
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* Find the largest closure, by closing all possible closures.
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* return the number of boxes closed in the maximum closure,
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* and the first box of the maximum closure in (x, y, dir)
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*/
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size_t ALGOR::find_max_closure(size_t& y, size_t& x, int& dir, const BOARD& b)
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{
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BOARD nb(b);
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int tdir, maxdir = -1;
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size_t nbox, maxbox = 0;
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size_t tx, ty, maxx = ~0, maxy = ~0;
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while ((nbox = count_closure(ty, tx, tdir, nb)) != 0)
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if (nbox > maxbox) {
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// This closure is better, update max
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maxbox = nbox;
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maxx = tx;
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maxy = ty;
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maxdir = tdir;
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}
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// Return the max found
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y = maxy;
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x = maxx;
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dir = maxdir;
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return maxbox;
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}
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// Find if a turn does not result in a capture on the given box
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// and return the direction if found.
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int ALGOR::try_good_turn(BOX& box, size_t y, size_t x, int& dir, BOARD& b)
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{
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// Sanity check; we must have a good box
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if (box.count() >= 2)
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b.abort("try_good_turn: box[%d,%d] has more than 2 sides occupied",
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y, x);
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// Make sure we don't make a closure in an adjacent box.
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// We use a random direction to randomize the game
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RANDOM rd(BOX::last);
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for (dir = rd(); dir < BOX::last; dir = rd())
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if (!box.isset(dir)) {
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size_t by = y + BOX::edges[dir].y;
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size_t bx = x + BOX::edges[dir].x;
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if (!b.bounds(by, bx))
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return 1;
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BOX nbox(by, bx, b);
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if (nbox.count() < 2)
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return 1;
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}
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return 0;
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}
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// Try to find a turn that does not result in an opponent closure, and
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// return it in (x, y, dir); if not found return 0.
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int ALGOR::find_good_turn(size_t& y, size_t& x, int& dir, const BOARD& b)
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{
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BOARD nb(b);
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RANDOM rdy(b.ny()), rdx(b.nx());
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for (y = rdy(); y < b.ny(); y = rdy()) {
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rdx.clear();
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for (x = rdx(); x < b.nx(); x = rdx()) {
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BOX box(y, x, nb);
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if (box.count() < 2 && try_good_turn(box, y, x, dir, nb))
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return 1;
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}
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}
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return 0;
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}
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// On a box with 2 edges, return the first or the last free edge, depending
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// on the order specified
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int ALGOR::try_bad_turn(BOX& box, size_t& y, size_t& x, int& dir, BOARD& b,
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int last)
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{
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if (4 - box.count() <= last)
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b.abort("try_bad_turn: Called at [%d,%d] for %d with %d",
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y, x, last, box.count());
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for (dir = BOX::first; dir < BOX::last; dir++)
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if (!box.isset(dir)) {
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if (!last)
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return 1;
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else
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last--;
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}
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return 0;
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}
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// Find a box that has 2 edges and return the first free edge of that
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// box or the last free edge of that box
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int ALGOR::find_bad_turn(size_t& y, size_t& x, int& dir, BOARD& b, int last)
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{
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RANDOM rdy(b.ny()), rdx(b.nx());
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for (y = rdy(); y < b.ny(); y = rdy()) {
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rdx.clear();
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for (x = rdx(); x < b.nx(); x = rdx()) {
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BOX box(y, x, b);
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if ((4 - box.count()) > last &&
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try_bad_turn(box, y, x, dir, b, last))
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return 1;
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}
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}
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return 0;
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}
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size_t ALGOR::find_min_closure1(size_t& y, size_t& x, int& dir, const BOARD& b,
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int last)
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{
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BOARD nb(b);
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int tdir, mindir = -1, xdir, mv;
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// number of boxes per closure
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size_t nbox, minbox = nb.nx() * nb.ny() + 1;
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size_t tx, ty, minx = ~0, miny = ~0;
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while (find_bad_turn(ty, tx, tdir, nb, last)) {
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// Play a bad move that would cause the opponent's closure
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if ((mv = nb.domove(ty, tx, tdir, getWho())) != 0)
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b.abort("find_min_closure1: Invalid move %d (%d, %d, %d)", mv,
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ty, tx, tdir);
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// Count the opponent's closure
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if ((nbox = count_closure(y, x, xdir, nb)) == 0)
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b.abort("find_min_closure1: no closure found");
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if (nbox <= minbox) {
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// This closure has fewer boxes
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minbox = nbox;
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minx = tx;
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miny = ty;
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mindir = tdir;
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}
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}
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y = miny;
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x = minx;
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dir = mindir;
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return minbox;
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}
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// Search for the move that makes the opponent close the least number of
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// boxes; returns 1 if a move found, 0 otherwise
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size_t ALGOR::find_min_closure(size_t& y, size_t& x, int& dir, const BOARD& b)
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{
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size_t x1, y1;
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int dir1;
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size_t count = b.ny() * b.nx() + 1, count1;
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for (size_t i = 0; i < 3; i++)
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if (count > (count1 = find_min_closure1(y1, x1, dir1, b, i))) {
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count = count1;
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y = y1;
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x = x1;
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dir = dir1;
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}
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return count != b.ny() * b.nx() + 1;
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}
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// Return a move in (y, x, dir)
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void ALGOR::play(const BOARD& b, size_t& y, size_t& x, int& dir)
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{
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// See if we can close the largest closure available
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if (find_max_closure(y, x, dir, b))
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return;
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#ifdef notyet
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size_t sgl = find_single();
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size_t dbl = find_double();
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#endif
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// See if we can play an edge without giving the opponent a box
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if (find_good_turn(y, x, dir, b))
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return;
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// Too bad, find the move that gives the opponent the fewer boxes
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if (find_min_closure(y, x, dir, b))
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return;
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}
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