aoc 2025, day 10, part 1

1 files changed, 180 insertions, 0 deletions

diff --git a/2025/src/day10.cpp b/2025/src/day10.cpp
new file mode 100644
index 0000000..f8e903d
--- /dev/null
+++ b/2025/src/day10.cpp
@@ -0,0 +1,180 @@
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+class Machine {
+public:
+        Machine(unsigned long dest, const vector<unsigned long>& buttons)
+            : dest_{ dest }
+            , buttons_{ buttons }
+        {
+        }
+
+        void push(size_t button)
+        {
+                curr_ ^= buttons_.at(button);
+                ++pushes_;
+        }
+
+        [[nodiscard]]
+        bool test() const
+        {
+                return curr_ == dest_;
+        }
+
+        void reset()
+        {
+                curr_   = 0;
+                pushes_ = 0;
+        }
+
+        [[nodiscard]]
+        unsigned long button_count() const
+        {
+                return buttons_.size();
+        }
+
+        [[nodiscard]]
+        unsigned long get_pushes() const
+        {
+                return pushes_;
+        }
+
+private:
+        unsigned long dest_;
+        unsigned long curr_{ 0 };
+        unsigned long pushes_{ 0 };
+
+        vector<unsigned long> buttons_;
+};
+
+vector<string>
+split(const string& str, const string& delims)
+{
+        vector<string> result;
+
+        size_t start = str.find_first_not_of(delims);
+        while ( start != string::npos ) {
+                size_t end = str.find_first_of(delims, start);
+
+                if ( end == string::npos ) {
+                        // letzter Teil
+                        result.push_back(str.substr(start));
+                        break;
+                }
+
+                result.push_back(str.substr(start, end - start));
+
+                start = str.find_first_not_of(delims, end);
+        }
+
+        return result;
+}
+
+vector<unsigned long>
+split(const string& str)
+{
+        stringstream          strm{ str };
+        vector<unsigned long> values;
+
+        for ( string part; getline(strm, part, ','); ) {
+                values.emplace_back(stoul(part));
+        }
+
+        return values;
+}
+
+unsigned long
+from_pattern(string pattern)
+{
+        unsigned long value = 0;
+        ranges::reverse(pattern);
+        for ( const char chr: pattern ) {
+                value <<= 1UL;
+                value |= (chr == '#') ? 1U : 0U;
+        }
+        return value;
+}
+
+unsigned long
+from_button_string(const string& pattern)
+{
+        unsigned long value = 0;
+        for ( const auto pos: split(pattern) ) {
+                value |= (1UL << pos);
+        }
+        return value;
+}
+
+vector<Machine>
+read_file(const filesystem::path& filename)
+{
+        ifstream file{ filename };
+
+        vector<Machine> machines;
+
+        for ( string line; getline(file, line); ) {
+                const auto parts = split(line, "[] (){}");
+
+                const auto dest = from_pattern(parts[0]);
+
+                vector<unsigned long> buttons;
+                for ( size_t i = 1; i < parts.size() - 1; ++i ) {
+                        buttons.emplace_back(from_button_string(parts[i]));
+                }
+
+                machines.emplace_back(dest, buttons);
+        }
+
+        return machines;
+}
+
+unsigned long
+simulate(Machine machine)
+{
+        auto min_so_far = numeric_limits<unsigned long>::max();
+
+        const auto button_count = machine.button_count();
+
+        for ( unsigned long i = 0; i != (1UL << button_count); ++i ) {
+                machine.reset();
+
+                for ( unsigned long button = 0; button != button_count; ++button ) {
+                        if ( (i & (1UL << button)) != 0 ) {
+                                machine.push(button);
+                        }
+                }
+
+                if ( machine.test() ) {
+                        min_so_far = min(min_so_far, machine.get_pushes());
+                }
+        }
+
+        return min_so_far;
+}
+
+void
+part1(const vector<Machine>& machines)
+{
+        unsigned long count = 0;
+        for ( const auto& machine: machines ) {
+                count += simulate(machine);
+        }
+        cout << "Part 1: " << count << '\n';
+}
+
+} // namespace
+
+int
+main()
+{
+        auto machines = read_file("data/day10.txt");
+        part1(machines);
+}