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
119
120
121
122
123
124
125
|
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
vector<string>
read_file(string_view filename)
{
fstream input{ filename };
vector<string> data;
for ( string line; getline(input, line); ) {
data.emplace_back(line);
}
return data;
}
vector<string>
split(const string& line, char sep)
{
vector<string> parts{};
stringstream input{ line };
for ( string part; getline(input, part, sep); ) {
parts.emplace_back(part);
}
return parts;
}
template<typename T = long>
vector<T>
read_ints(const string& line)
{
vector<T> parts{};
stringstream input{ line };
for ( string part; getline(input, part, ','); ) {
parts.emplace_back(stol(part));
}
return parts;
}
vector<long>
count_groups(string_view str)
{
vector<long> groups;
size_t idx = 0U;
while ( idx != str.length() ) {
while ( idx != str.length() && str[idx] == '.' ) {
++idx;
}
if ( idx != str.length() && str[idx] == '#' ) {
auto num = 0L;
while ( idx != str.length() && str[idx] == '#' ) {
++num;
++idx;
}
groups.emplace_back(num);
}
}
return groups;
}
long
brute_force(string_view puzzle, const vector<long>& nums)
{
long counts = count_if(puzzle.begin(), puzzle.end(), [](char chr) { return chr == '?'; });
string test_pattern;
auto arrangements = 0L;
for ( size_t counter = 0; counter != (1U << size_t(counts)); ++counter ) {
auto bit_pattern = counter;
for ( char chr: puzzle ) {
if ( chr == '?' ) {
if ( (bit_pattern & 1U) != 0U ) {
test_pattern += '.';
}
else {
test_pattern += '#';
}
bit_pattern >>= 1U;
}
else {
test_pattern += chr;
}
}
if ( nums == count_groups(test_pattern) ) {
arrangements++;
}
test_pattern.clear();
}
return arrangements;
}
void
part1(const vector<string>& input)
{
auto sum = 0L;
for ( const auto& line: input ) {
auto parts = split(line, ' ');
auto puzzle = parts[0];
auto nums = read_ints(parts[1]);
sum += brute_force(puzzle, nums);
}
cout << sum << endl;
}
int
main()
{
const auto input = read_file("data/day12.txt");
part1(input);
}
|
