1 files changed, 97 insertions, 0 deletions

diff --git a/2015/src/day07.cpp b/2015/src/day07.cpp
new file mode 100644
index 0000000..f24d5af
--- /dev/null
+++ b/2015/src/day07.cpp
@@ -0,0 +1,97 @@
+#include <cinttypes>
+#include <cstdio>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+auto
+read_file(string_view filename)
+{
+        fstream             input{ filename };
+        map<string, string> deps;
+
+        for ( string line; getline(input, line); ) {
+                const auto pos = line.find(" -> ");
+                if ( pos == string::npos ) {
+                        continue;
+                }
+
+                deps[line.substr(pos + 4)] = line.substr(0, pos);
+        }
+
+        return deps;
+}
+
+// NOLINTBEGIN
+uint16_t
+solve(map<string, string>& deps, const string& dep)
+{
+        map<string, uint16_t> cache;
+
+        function<uint16_t(const string&)> solve = [&](const string& dep) -> uint16_t {
+                if (cache.contains(dep)) {
+                        return cache[dep];
+                }
+
+                uint16_t value = 0;
+                if (sscanf(dep.c_str(), "%" SCNu16, &value) == 1) {
+                        return cache[dep] = value;
+                }
+
+                const auto& line = deps[dep];
+
+                static const size_t MAX = 11;
+                char lhs[MAX], rhs[MAX];
+
+                if ( sscanf(line.c_str(), "%10s AND %10s", lhs, rhs) == 2 ) {
+                        value = solve(lhs) & solve(rhs);
+                }
+                else if ( sscanf(line.c_str(), "%10s OR %10s", lhs, rhs) == 2 ) {
+                        value = solve(lhs) | solve(rhs);
+                }
+                else if ( sscanf(line.c_str(), "%10s LSHIFT %10s", lhs, rhs) == 2 ) {
+                        value = static_cast<uint16_t>(solve(lhs) << solve(rhs));
+                }
+                else if ( sscanf(line.c_str(), "%10s RSHIFT %10s", lhs, rhs) == 2 ) {
+                        value = static_cast<uint16_t>(solve(lhs) >> solve(rhs));
+                }
+                else if ( sscanf(line.c_str(), "NOT %10s", lhs) == 1 ) {
+                        value = ~solve(lhs);
+                }
+                else {
+                        value = solve(line);
+                }
+
+                return cache[dep] = value;
+        };
+
+        return solve(dep);
+}
+// NOLINTEND
+
+auto
+part1(map<string, string>& deps)
+{
+        auto result = solve(deps, "a");
+        cout << result << endl;
+        return result;
+}
+
+void
+part2(map<string, string>& deps, uint16_t result)
+{
+        deps["b"] = to_string(result);
+        cout << solve(deps, "a") << endl;
+}
+
+int
+main()
+{
+        auto deps = read_file("data/day07.txt");
+        auto result = part1(deps);
+        part2(deps, result);
+}