1 files changed, 100 insertions, 1 deletions
diff --git a/src/2017/day23/aoc.cpp b/src/2017/day23/aoc.cpp
index 444cec9..7d990e3 100644
--- a/src/2017/day23/aoc.cpp
+++ b/src/2017/day23/aoc.cpp
@@ -2,5 +2,104 @@
 
 namespace aoc2017 {
 
-std::pair<int64_t, int64_t> day23(line_view) { return {0, 0}; }
+static int64_t& get(char x, int64_t rs[26]) { return rs[x - 'a']; }
+static void get_number(const char** pp, int64_t* d) {
+  const char* p = *pp;
+  int sign = 1;
+  if (*p == '-') {
+    sign = -1;
+    p++;
+  }
+  while (*p >= '0' && *p <= '9') {
+    *d = *d * 10 + *p - '0';
+    p++;
+  }
+  *d *= sign;
+  *pp = p;
+}
+
+static int64_t get_number(const char* p, int64_t rs[26]) {
+  int64_t d{0};
+  if (*p == '-' || (*p >= '0' && (*p <= '9'))) {
+    get_number(&p, &d);
+  } else {
+    d = get(*p, rs);
+  }
+  return d;
+}
+
+typedef void (*f23)(size_t* i, const char* p1, const char* p2, int64_t rs[26]);
+
+static void set(size_t* i, const char* p1, const char* p2, int64_t rs[26]) {
+  get(*p1, rs) = get_number(p2, rs);
+  *i += 1;
+}
+
+static void sub(size_t* i, const char* p1, const char* p2, int64_t rs[26]) {
+  get(*p1, rs) -= get_number(p2, rs);
+  *i += 1;
+}
+
+static void mul(size_t* i, const char* p1, const char* p2, int64_t rs[26]) {
+  get(*p1, rs) *= get_number(p2, rs);
+  *i += 1;
+}
+
+static void jnz(size_t* i, const char* p1, const char* p2, int64_t rs[26]) {
+  auto d1 = get_number(p1, rs);
+  auto d2 = get_number(p2, rs);
+  *i += d1 != 0 ? d2 : 1;
+}
+
+static struct {
+  f23 f;
+  const char* s;
+  int c;
+} fs[4] = {{set, "set", 0}, {sub, "sub", 0}, {mul, "mul", 0}, {jnz, "jnz", 0}};
+
+static size_t exec(size_t index, const std::vector<line_view>& todos, int64_t rs[26]) {
+  if (index < todos.size()) {
+    auto& todo = todos[index];
+    const char* p = todo.line;
+    auto match = [](const char* p, const char* p0) -> bool {
+      for (int i = 0; i < 3; i++) {
+        if (*(p + i) != *(p0 + i)) {
+          return false;
+        }
+      }
+      return true;
+    };
+
+    for (auto& fx : fs) {
+      if (match(p, fx.s)) {
+        fx.c += 1;
+        fx.f(&index, p + 4, p + 6, rs);
+        break;
+      }
+    }
+  }
+  return index;
+}
+
+static void part1(const std::vector<line_view>& todos) {
+  size_t index{0};
+  int64_t rs[26] = {0};
+
+  while (index < todos.size()) {
+    index = exec(index, todos, rs);
+  }
+}
+
+std::pair<int64_t, int64_t> day23(line_view file) {
+  std::vector<line_view> todos;
+  per_line(file, [&todos](line_view lv) {
+    todos.push_back(lv);
+    return true;
+  });
+
+  part1(todos);
+  int64_t t0 = fs[2].c;
+
+  return {t0, 0};
+}
 } // namespace aoc2017