Lösung für Tag 12, Teil 1

1 files changed, 126 insertions, 0 deletions

diff --git a/src/day12.cpp b/src/day12.cpp
new file mode 100644
index 0000000..31a2739
--- /dev/null
+++ b/src/day12.cpp
@@ -0,0 +1,126 @@
+#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 auto input = read_file("data/day12.txt");
+
+        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()
+{
+        part1();
+}