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
105
106
107
108
109
110
111
112
113
114
115
116
117
118
|
#pragma once
#include "common.h"
#include <algorithm>
#include <math.h>
#include <set>
#include <vector>
#include <functional>
namespace aoc2016 {
struct instruction {
enum {
left = 0,
right,
} direction;
int distance = 0;
};
struct position {
enum bearing {
north = 0,
east,
south,
west,
} b;
int x;
int y;
bool operator<(const position& p) const noexcept { return x < p.x ? true : (x > p.x ? false : y < p.y); }
int blocks(position p) const noexcept { return abs(p.x - x) + abs(p.y - y); }
position move(instruction i) const noexcept {
auto putx = [this](int d) { return x; };
auto puty = [this](int d) { return y; };
auto addx = [this](int d) { return x + d; };
auto subx = [this](int d) { return x - d; };
auto addy = [this](int d) { return y + d; };
auto suby = [this](int d) { return y - d; };
struct {
bearing bs[2];
std::function<int(int)> lr[4];
} moves[] = {
{{west, east}, {subx, addx, puty, puty}},
{{north, south}, {putx, putx, addy, suby}},
{{east, west}, {addx, subx, puty, puty}},
{{south, north}, {putx, putx, suby, addy}},
};
position next;
next.b = moves[int(b)].bs[int(i.direction)];
next.x = moves[int(b)].lr[int(i.direction)](i.distance);
next.y = moves[int(b)].lr[int(i.direction) + 2](i.distance);
return next;
}
std::vector<position> line(position p1, position p2) const noexcept {
std::vector<position> ps;
auto copyx = [&p1, &p2, &ps](int x) {
if (x > 0) {
for (int i = p1.x; i < p2.x; i++) {
ps.push_back({p2.b, i, p1.y});
}
}
if (x < 0) {
for (int i = p1.x; i > p2.x; i--) {
ps.push_back({p2.b, i, p1.y});
}
}
};
auto copyy = [&p1, &p2, &ps](int y) {
if (y > 0) {
for (int i = p1.y; i < p2.y; i++) {
ps.push_back({p2.b, p1.x, i});
}
}
if (y < 0) {
for (int i = p1.y; i > p2.y; i--) {
ps.push_back({p2.b, p1.x, i});
}
}
};
copyx(p2.x - p1.x);
copyy(p2.y - p1.y);
return ps;
}
void cross(position p1, position p2, position* first, bool* found) const noexcept {
static std::set<position> ps = {};
if (!(*found)) {
auto v = line(p1, p2);
for (size_t i = 0; i < v.size(); i++) {
// printf("%d %d %d\n", int(v[i].b), v[i].x, v[i].y);
auto p = ps.insert(v[i]);
if (!p.second) {
*found = true;
*first = *p.first;
return;
}
}
}
}
position move(const std::vector<instruction>& is, position* first, bool* found) const noexcept {
position next = *this;
std::for_each(is.begin(), is.end(), [&next, first, found, this](const instruction& i) {
position prev = next;
next = next.move(i);
cross(prev, next, first, found);
});
return next;
}
};
std::pair<int, int> day1(line_view);
} // namespace aoc2016
|
