1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
//-----------------------------------------------------------------------------
/** @file libpentobi_mcts/StateUtil.cpp
@author Markus Enzenberger
@copyright GNU General Public License version 3 or later */
//-----------------------------------------------------------------------------
#include "StateUtil.h"
namespace libpentobi_mcts {
using namespace std;
using libpentobi_base::Color;
using libpentobi_base::ColorMove;
using libpentobi_base::Geometry;
using libpentobi_base::Point;
using libpentobi_base::PointState;
//-----------------------------------------------------------------------------
namespace {
array<Color::IntType, Color::range> symmetric_state{ {1, 0, 3, 2} };
} // namespace
//-----------------------------------------------------------------------------
bool check_symmetry_broken(const Board& bd)
{
LIBBOARDGAME_ASSERT(has_central_symmetry(bd.get_variant()));
auto& symmetric_points = bd.get_board_const().get_symmetrc_points();
Color to_play = bd.get_to_play();
auto& geo = bd.get_geometry();
// No need to iterate over the whole board when checking symmetry (this
// makes the assumption that the symmetric points of the points in the
// first half of the integer range are in the second half).
Geometry::Iterator begin = geo.begin();
LIBBOARDGAME_ASSERT(geo.get_range() % 2 == 0);
Geometry::Iterator end(static_cast<Point::IntType>(geo.get_range() / 2));
#ifdef LIBBOARDGAME_DEBUG
for (auto p = begin; p != end; ++p)
LIBBOARDGAME_ASSERT(symmetric_points[*p].to_int() >= (*end).to_int());
#endif
if (to_play == Color(0) || to_play == Color(2))
{
// First player to play: the symmetry is broken if the position is
// not symmetric.
for (auto p = begin; p != end; ++p)
{
PointState s1 = bd.get_point_state(*p);
if (! s1.is_empty())
{
Point symm_p = symmetric_points[*p];
PointState s2 = bd.get_point_state(symm_p);
if (s2.to_int() != symmetric_state[s1.to_int()])
return true;
}
}
}
else
{
// Second player to play: the symmetry is broken if the second player
// cannot copy the first player's last move to make the position
// symmetric again.
unsigned nu_moves = bd.get_nu_moves();
if (nu_moves == 0)
// Don't try to handle the case if the second player has to play as
// first move (e.g. in setup positions)
return true;
Color previous_color = bd.get_previous(to_play);
ColorMove last_mv = bd.get_move(nu_moves - 1);
if (last_mv.color != previous_color)
// Don't try to handle non-alternating moves in board history
return true;
auto points = bd.get_move_points(last_mv.move);
for (Point p : points)
if (! bd.get_point_state(symmetric_points[p]).is_empty())
return true;
for (auto p = begin; p != end; ++p)
{
PointState s1 = bd.get_point_state(*p);
if (! s1.is_empty())
{
PointState s2 = bd.get_point_state(symmetric_points[*p]);
if (s2.to_int() != symmetric_state[s1.to_int()]
&& ! points.contains(*p))
return true;
}
}
}
return false;
}
//-----------------------------------------------------------------------------
} // namespace libpentobi_mcts
|
