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
97
98
99
100
101
102
103
104
|
#include <filesystem>
#include <fstream>
#include <iostream>
#include <tuple>
#include <vector>
// Geos
#include <geos/geom/CoordinateSequence.h>
#include <geos/geom/GeometryFactory.h>
#include <geos/geom/Polygon.h>
using namespace std;
using namespace geos;
using namespace geos::geom;
namespace {
using Pos = tuple<long, long>; // (x, y)
vector<Pos>
read_file(const filesystem::path& filename)
{
ifstream file{ filename };
vector<Pos> data;
long x{};
long y{};
char skip{};
while ( file >> x >> skip >> y ) {
data.emplace_back(x, y);
}
return data;
}
std::unique_ptr<Polygon>
makePolygon(const std::vector<Pos>& pts)
{
CoordinateSequence coords;
for ( const auto [x, y]: pts ) {
coords.add(static_cast<double>(x), static_cast<double>(y));
}
// polygon schließen
coords.add(static_cast<double>(get<0>(pts[0])), static_cast<double>(get<1>(pts[0])));
const auto* factory = GeometryFactory::getDefaultInstance();
auto shell = factory->createLinearRing(coords);
return factory->createPolygon(std::move(shell), {});
}
void
part2_geos(const vector<Pos>& data)
{
auto poly = makePolygon(data);
auto max_area = numeric_limits<long>::min();
for ( size_t i = 0; i != data.size(); ++i ) {
for ( size_t j = i + 1; j != data.size(); ++j ) {
const auto [x1, y1] = data[i];
const auto [x2, y2] = data[j];
const auto width = abs(x1 - x2) + 1;
const auto height = abs(y1 - y2) + 1;
const auto area = width * height;
if ( area <= max_area ) {
continue;
}
const auto left = min(x1, x2);
const auto right = max(x1, x2);
const auto top = min(y1, y2);
const auto bottom = max(y1, y2);
auto rect = makePolygon(vector<Pos>{
make_tuple(left, top),
make_tuple(right, top),
make_tuple(right, bottom),
make_tuple(left, bottom),
make_tuple(left, top),
});
if ( poly->covers(rect.get()) ) {
max_area = area;
}
}
}
cout << "Part 2: " << max_area << '\n';
}
} // namespace
int
main()
{
auto data = read_file("data/day09.txt");
part2_geos(data);
}
|
